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SSLC Physics Chapter 4 Reflection of Light Textbook Questions and Answers

SCERT Class 10th Standard Physics Chapter 4 Reflection of Light Solutions

Text Book Page No. 80

Sslc Physics Chapter 4 Kerala Syllabus Question 1.

→ Which is the incident ray?
Answer:
AO

→ Which is the reflected ray?
Answers:
QB

→ Is there any relation between the angle of incidence and the angle of reflection?
Answer:
The angle of incidence and angle of reflection are equal.

→ Are the incident ray, reflected ray and normal to the mirror at the point of incidence in the different planes?
Answer:
In the same plane.

Reflection Of Light Class 10 Kerala Syllabus Question 2.

→ What difference is seen between the surfaces of the two objects?
Answer:
In the first figure the surface is smooth, in the second figure surface is rough.

→ Fig. 4.2(b) are the rays of light travelling parallel after reflection?
Answer:
No. When light falls on a rough surface, it undergoes an irregular reflection. This is scattered reflection.

Reflection of Light Class 10 Question 3.
In Fig. 4.2(a) regular reflection is depicted. Can you give a definition for such reflections by observing the figure?
Answer:
When light falls on a smooth surface, it undergoes an regular reflection, the rays of light travelling parallel after reflection This is regular reflection.

Text Book Page No. 81

Sslc Physics Chapter 4 Notes Kerala Syllabus Question 4.
Record in your science diary the following features about the images formed here.

→ The distance from the mirror to the object and the image from the mirror.
Answer: Equal

→ Is the image real or virtual?
Answer: Virtual

→ The size of the image.
Answer:
Same size as object.

Sslc Physics Reflection Of Light Kerala Syllabus Question 5.
How many images can we see at a time busying two mirrors?
Answer:
The number of images changes accordance with the relation between the angle between the mirrors.

Text Book Page No. 82

Sslc Physics Chapter 4 Reflection Of Light Kerala Syllabus Question 6.
Table 4.1.

Answer:

→ How many images can be seen when viewed from A and B?
Answer:
3

→ What if viewed from other positions in between the mirrors?
Answer:
3

→ How much is the angle between the mirrors?
Answer:
90°

→ What is the relation between the angle between the mirrors and the number of images?
Answer:
Number of images = \(n=\frac{360}{\theta}-1\)

Class 10 Physics Chapter 4 Reflection Of Light Kerala Syllabus Question 7.
Table 4.2.

Answer:

Text Book Page No. 83

Class 10 Physics Chapter 4 Kerala Syllabus Question 8.

Answer:

Text Book Page No. 84

Sslc Physics Chapter 4 Solutions Kerala Syllabus Question 9.
Draw a straight line on a table as shown in the figure. At one end of the line, place a concave mirror of focal length 20 cm. Mark principal focus (F) and center of curvature (C) on the line.

Fix a burning candle on the principal focus in such a way that it is at a slight distance from the center of curvature. Arrange a screen in such a way that a clear image is obtained on the screen.

→ What is the position and features of the image?
Answer:
Between F and C, small, real, inverted.

→ Observe the change in position of image and features on changing the position of the candle
Answer:

Physics Chapter 4 Class 10 Kerala Syllabus Question 10.
Table 4.4.

Answer:

Physics Class 10 Chapter 4 Kerala Syllabus Question 11.
Aren’t the focal length of \(\frac{u v}{u+v}\) the mirror and the average value of obtained from the table the same?
Answer:
Yes

Text Book Page No. 85

Sslc Physics Chapter 4 Reflection Of Light Notes Kerala Syllabus Question 12.
Record the measurements shown in the figure (4.6) using the New Cartesian Sign Convention.

→ Distance to the object from the mirror (u) =
Answer:
Negative.

→ Distance to the image from the mirror (v) =
Answer:
Negative.

→ Height of object (OB) =
Answer:
Positive.

→ Height of image (IM) =
Answer:
Negative.

Text Book Page No. 86

Kerala Syllabus 10th Standard Physics Chapter 4 Question 13.
The given figure shows the image formation by a concave mirror. Analyse the figure and write down different measures using New Cartesian Sign Convention.

Answer:

Sslc Physics Chapter 4 Notes Pdf Kerala Syllabus Question 14.
An object is placed in front of a concave mirror 20 cm away from it. If its focal length is 40 cm, locate the position of image and its nature.
Answer:
f = – 40 cm, u = – 20 cm
f = \(\frac { uv }{ u+v }\)
– 40 = \(\frac { – 20 }{ – 20 + v }\)
– 40 ( – 20 + v ) = – 20 v
– 20 + v = \(\frac { – 20 }{ – 40 }\) = \(\frac { 2 }{ v }\)
– 20 = [/latex] = \(\frac { v }{ 2 }\) – v = – \(\frac { v }{ 2 }\)
∴ – \(\frac { v }{ 2 }\) = – 20
v = 40 cm
Features of image:
At behind the mirror, very large, virtual, direct.

10th Physics Chapter 4 Kerala Syllabus Question 15.
Find out the height of object (ho), height of image (hi), position of object(u) and position of image (v) using New Cartesian Sign Convention and tabulate them. (The height of image hi can be directly measured by fixing a graph paper on the screen).
Answer:

Text Book Page No. 87

Physics Class 10 Chapter 4 Kerala Syllabus Question 16.
\(\frac{h_{i}}{h_{o}}\) is magnification. Does it have any relational with the value of \(\frac{v}{u}\) ?
Answer:
\(m=\frac{-h_{i}}{h_{o}}=\frac{-v}{u}\)

Text Book Page No. 88

Question 17.
An object is placed 8 cm away in front of a concave mirror of focal length 5 cm. Find out the position of image and magnification. Find out whether the image is inverted or erect by drawing the ray diagram on a graph paper.
Answer:
f = – 5 cm, u = – 8 cm

Features of images : Beyond C, big, real, inverted

Question 18.
What are the features of an image that is obtained from magnification?
Answer:

• When magnification is 1, the size of the image and the size of the object are equal.
• When magnification is more than 1, the size of the image is greater than the size of the object.
• When magnification is less than 1, the size of the image is smaller than the size of the object.
• When the magnification is positive, image is real and inverted.
• When the magnification is negative, image is virtual and erect.

Question 19.
Observe the given figures and complete the table using New Cartesian Sign Convention.

Answer:

Text Book Rage No. 89

Question 20.

From the above table, find out which mirror always gives an erect and diminished image and write it down.
Answer:
The image formed by a convex mirror is always erect and diminished.

Question 21.
Why it is written on rearview mirrors that “Objects in the mirror are closer than they appear”.
Answer:
The image formed by a convex mirror is always erect and diminished. Hence the driver who sees the image of vehicles on the mirror develops a feeling that the vehicles coming from behind are at a greater distance. This may turn out to be dangerous.

Reflection of Light Let Us Assess

Question 1.
A dental doctor uses a mirror of focal length 8 cm. To see the teeth clearly what should be the maximum distance between the teeth and the mirror? Justify your answer. Which type of mirror has been used by the doctor?
Answer:
The dental doctor uses a concave mirror. Effect and enlarged image can be obtained using the mirror. Such images are formed when the object is kept in between the main focus and pole of a concave mirror. So the minimum distance between the mirror and the teeth must be in 8 cm to view the teeth clearly.

Question 2.
Imagine that a spherical mirror gives an image magnified 5 times at a distance 5 m. If so determine whether the mirror is concave or convex. How much will be the focal length of the mirror?
Answer:

Image formed is larger than the object, so the used mirror is concave.

Question 3.
A motorcyclist observes a car coining from behind with a magnification 1/6. If the actual distance between the car and the bike is 30 m calculate the radius of curvature of the mirror.
Answer:

Question 4.
A shaving mirror of focal length 72 cm is kept in a beauty clinic. A man uses it standing 18 cm away from the mirror. At what distance will the image be formed? Is the image real or virtual? What is the magnification of the image?
Answer:
f =-72 cm, u = -18cm

Image formed on the 24 cm away from the mirror. Virtual image.
Magnification.
m = \(\frac{-v}{u}=-\frac{24}{18}\) = – 1.33
This is a concave mirror.

Question 5.
Wrap a rubber ball of diameter 12 cm completely with an aluminum foil and make the surfaces smooth. Where will be the image of an object kept 12 cm away from the center of the ball? Is the image real or virtual?
Answer:
Surface of a rubber ball is similar to a convex mirror.
Diameter = 12 cm
⇒ Radius = 6 cm
2f = R
f = \(\frac { R }{ 2 }\) = \(\frac { 6 }{ 2 }\) = 3 cm
u = \(\frac { 12 }{ 2 }\) = 6 cm

Mirror is a convex, so image is virtual.

Question 6.
We are able to read a book since light falling on a surface gets reflected from the book and reaches the eye. But on such occasions, we cannot see our images like that from a mirror. Explain why?
Answer:
Irregular reflection takes place in the book. So images not formed.

Question 7.
Is the image formed by a plane mirror real or virtual? Write an instance when such a mirror gives an inverted image.
Answer:
Image formed by a plane mirror is always direct and virtual. The image will be at the same distance at the object.

If the objects placed erect as shown in the figure then the image will be inverted.

Reflection of Light Exam Oriented Questions and Answers

Very Short Answer Type Questions (Score 1)

Question 1.
1. Classify the following statements as to those related to concave mirrors and convex mirrors and tabulate them accordingly.
a. to view the face.
b. as makeup mirror.
c. as reviewer mirrors in vehicles.
d. in solar concentration.
e. in periscopes.
f. as shaving mirror.
Answer:
Concave mirror:

• In solar concentration.
• Makeup mirror.
• Shaving mirror.

Convex mirror:

• In rearview mirrors of vehicles.
• In Searchlights.

Plane mirror:

• In periscopes.
• To see face.

Question 2.
Find out the relation and All in the blanks.
Small, virtual and direct images:
Convex mirror.
Size same as object, virtual and direct image :………………
Answer:
Plane mirror.

Question 3.
Which mirror gives rectifiable whatever the distance between the object and mirror is
i. Plane mirror.
ii. Convex mirror.
iii. Concave mirror.
iv. Plane or convex mirror.
Answer:
Plane or convex mirror.

Question 4.
Relation between angle of incidence (i) and angle of reflection (r) of light is………..
i. i > r
ii. i < r
iii. i = r
iv. None of these
Answer:
iii. i = r

Question 5.
Find the odd one in the group.
More scattered reflection, virtual image, direct image, large image
Answer:
Large image.

Very Short Answer Type Questions (Score 2)

Question 6.
Radius of curvature of a concave mirror is 24 cm. Then find the focal length of the mirror?
Answer:
R = 24 cm
f = \(\frac{R}{2}=\frac{24}{2}\) = 12 cm

Question 7.
Find the radius of curvature of a convex mirror whose focal length is 0.6 m.
Answer:
f = \(\frac{\mathrm{R}}{2}\)
∴ R=2f
0.6 = \(\frac{R}{2}\)
R = 2 × 0.6 = 1.2 m

Question 8.
Write the characteristics of the image formed by an object placed at the center of curvature of a concave mirror?
Answer:
Position: At the center of curvature at the same side
Size: Same as the size of the object
Nature: Real, Inverted

Question 9.
i. Which are the different types of mirror?
ii. What are the peculiarities are images obtained in the face mirror?
Answer:
i. Convex, concave and plane mirror.
ii. Image will be formed behind the mirror and will be equal distance from the mirror to the object. It will be direct and virtual.

Question 10.
State whether the below-given statement are true or false. If false correct them.
i. Real images are always produced by concave mirror.
ii. The image formed from a convex mirror is direct and enlarged.
Answer:
i. False. If the position of object is between focus and pole, virtual image is produced by concave mirror.
ii.False. The image formed by convex mirror will be smaller than the object and erect.

Very Short Answer Type Questions (Score 3)

Question 11.
Write three differences of real image and virtual image which is made by spherical mirrors.
Answer:
Real images:

• Inverted.
• Can be shown on a screen.
• Can measure the length of the image and distance to the image.

Virtual images:

• Cannot be taken on a screen.
• Not able to be measured direct.

Question 12.
Write the uses of concave mirror?
Answer:

• Used as a shaving mirror.
• Used as a makeup mirror.
• Doctors used as head mirrors.
• On film projectors.

Question 13.

a. Examine the figure and find the magnification.
b. What is the height of the object if height of the image is 4 cm when the object is placed on the same position in front of the mirror.
Answer:
a. Magnification = \(=\frac{\mathrm{hi}}{\mathrm{ho}}=\frac{– 10}{5}=– 2\)

Question 14.
Write the uses of convex mirror?
Answer:

• As reflectors in street lights.
• As rear view mirrors in vehicles.
• In searchlights.

Question 15.
Examine the position of the object given in the figure and table the following peculiarities.

a. Position of image.
b. Size of image.
c. Features of image.
Answer:
a.Behind the mirror.
b.Larger than obj etc.
c. Direct, virtual.

Question 16.
When an object of height 4 cm is placed in front of a concave mirror an image of height 8 cm is formed. Find the magnification.
Answer:
Magnification
hi = 4 cm, ho =  – 8 cm
Magnification m = \(\frac { hi }{ h0 }\) = \(\frac { –8 }{ 4 }\) = – 2

Very Short Answer Type Questions (Score 4)

Question 17.
Complete the table.

Answer:
a. Passes through principal focus.
b.Seem to come from the principal focus.
c, d. Returns parallel to the principal axis.
e, f. Returns through the same path.
g, h. Reflects in the same angle of incident ray.

Question 18.
Complete the ray diagram.


Answer:

Question 19.
Complete the table.

Answer:
a. 30°
b. 40°
c. 50°
d. 60°

Question 20.
An object of 5 cm is kept in front of a convex mirror having radius of curvature 30 cm at a distance of 10 cm. Calculate the position, size, and feature of object.
Answer:
u = – 10 cm
v = ?
Focal length = \(\frac{r}{2}=\frac{30}{2}\) = + 15 cm

The image is formed 60cm behind the concave mirror. The’ image will be virtual and direct.

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SSLC Maths Chapter 9 Geometry and Algebra Textbook Questions and Answers

SCERT Class 10th Standard Maths Chapter 9 Geometry and Algebra Notes

Textbook Page No. 213

Geometry and Algebra Class 10 Solutions Question 1.
What are the coordinates of the fourth vertex of the parallelogram shown on the right?

Answer:
Coordinate of the fourth vertex is = (6, 6)

Geometry and Algebra Class 10 Question 2.
The Figure shows a parallelogram with the coordinates of its vertices:
Prove that x₁ + x₃ = x₂ + x₄ and y₁ + y₃ = y₂ + y₄.

Answer:
Let P be the; point of intersection of diagonals of a parallelogram, which is the midpoint of AB and OC.

From eqn (1)
Comparing y coordinates

Geometry And Algebra Class 10 Chapter 9 Kerala Syllabus Question 3.
A parallelogram is drawn with the lines joining (x₁, y₁) aid (x_2, y₂) to the origin as adjacent sides. What are the coordinates of the fourth vertex?

Answer:
Coordinates of the fourth vertex = (x₁ + x₂, y₁ + y₂)
Let P be the point of intersection of diago¬nals of a parallelogram, which is the midpoint of AB and OC.

Sslc Maths Chapter 9 Kerala Syllabus Question 4.
Prove that in any parallelogram, the sum of the squares of all sides is equal to the sum of the squares of the diagonals.
Answer:

OA² + OB² = x₁² + y₁²  + x₂²  + y₂²
OA = BC and OB = AC
OA² + OB² + OC² + AC² = 2(x₁² + y₁² + x₂² + y₂² )
AB² = (x₂ – x₁ )² + (y₂ – y₁ )²
OC² = (x₁ – x₂)² + (y₂ – y₃)²
OB² + OC² = 2(x₁² + x₂² + y₁² + y₂²)
OA² + OB² + AC² + BC² = AB² + OC²

Sslc Maths Geometry And Algebra Chapter 9 Kerala Syllabus Question 5.
In this picture, the midpoints of the sides of the large triangle are joined to make a small triangle inside. Calculate the coordinates of die vertices of the large triangle.
Answer:

textbook page no: 217

Sslc Geometry And Algebra Chapter 9 Kerala Syllabus Question 1.
A circle is drawn with the line joining (2, 3) and (6, 5) as diameter. What are the coordinates of the centre of the circle?
Answer:
Midpoint of the line joining (2, 3) and (6, 5) is

Sslc Maths Chapter 9 Solutions Kerala Syllabus Question 2.
The coordinates of two opposite vertices of a parallelogram are (4, 5) and (1, 3). What are the coordinates of the point of intersection of its diagonals?
Answer:
Midpoint of line joining the points (4, 5) and (1, 3) is

The coordinates of the point of intersec¬tion of its diagonal is (3, 4).

Geometry And Algebra Class 10 Solutions Chapter 9 Kerala Syllabus Question 3.
The coordinates of the vertices of a quadrilateral, taken in order, are (2, 1), (5, 3), (8, 7), (4, 9).
i. Find the coordinates of the midpoints of all four sides.
ii. Prove that the quadrilateral got by joining these midpoints is a parallelogram.
Answer:


Since the opposite sides of the quadrilateral PQRS are equal it is a parallelogram.

Geometry And Algebra Sslc Chapter 9 Kerala Syllabus Question 4.
In the figure, the midpoints of the large quadrilateral are joined to form the small quadrilateral within:
i. Find the coordinates of the fourth vertex of the smaller quadrilateral.
ii. Find the coordinates of the other three vertices of the larger quadrilateral.

Answer:

Midpoint of AB is P

Coordinate of the fourth vertex of smaller quadrilateral -(6, 2)
ii. Coordinates of other three vertices of the bigger quadrilateral (10, 3),(8, 7),(4, 5)

Geometry And Algebra Class 10 Kerala Syllabus Chapter 9 Kerala Syllabus Question 5.
The coordinates of the vertices of a triangle are (3, 5), (9, 13), (10, 6). Prove that this triangle is isosceles. Calculate its area.
Answer:
IfA (3, 5), B (9, 13), C(10, 6)
are the vertices of the triangle ABC

As BC = AC the triangle is an isosceles triangle

Geometry And Algebra Class 10 Pdf Chapter 9 Kerala Syllabus Question 6.
The centre of a circle is (1, 2) and a point on it is (3, 2). Find the coordinates of the other end of the diameter through this point
Answer:
Midpoint of the diameter

textbook Page no: 220

Geometry And Algebra Class 10 Questions And Answers Chapter 9 Kerala Syllabus  Question 1.
The coordinates of the points A and Bare (3, 2) and (8, 7). Find the coordinates of
i. the point P on AB with AP: PB = 2 : 3
ii. the point Q on AB with AQ: QB = 3: 2
Answer:

Geometry And Algebra Class 10 Scert Chapter 9 Kerala Syllabus Question 2.
Find the coordinates of the points which divide the line joining (1, 6) and (5, 2) into three equal parts.
Answer:

Coordinate of Q is \(\left(\frac{11}{3}, \frac{10}{3}\right)\)

Algebra Solutions Question 3. The coordinates of the vertices of a triangle are (-1, 5), (3, 7), (1, 1). Find the coordinates of its centroid.
Answer:
Centroid of the triangle

Question 4.
Calculate the coordinates of the point Pin the picture:

Answer:
Bisector of an angle divides the opposite side in the ratio of the sides containing the angle.

So, the coordinates of the point P which divides the line joining (4, 0) and (0, 3) in the ratio 4 : 3.
BP : PC = 4 : 3, so coordinate of P is Coordinate of x \(=4+\frac{4}{7}(0-4)=4-\frac{16}{7}=\frac{12}{7}\)
Coordinate of y \(=0+\frac{4}{7}(3-0)=0+\frac{12}{7}=\frac{12}{7}\)
\(\text { Coordinate of } P \text { is }\left(\frac{12}{7}, \frac{12}{7}\right)\)

Textbook Page No. 227

Question 1.
Prove that the points (1, 3), (2, 5), (3, 7) are on the same line.
Answer:
Coordinates of slope of a line, which joins the points (1, 3) and (2, 5) = \(\frac{5-3}{2-1}=2\)
Slope of a line, which joins the points (2, 5) and (3, 7) \(=\frac{7-5}{3-2}=2\)
both have same slope, so they make equal angles with the x-axis.
∴ They all lie on the same line.

Algebra 10th Standard Question 2. Find the coordinates of two more points on the line joining (-1, 4) and (1, 2).
Answer:
Change in x is 2 and y is -2
When change in x be 1 then change in y = \(\frac{-2}{2}=-1\)
Let change in x be 1 then change in y will be 3.
Coordinate of y = 4 + 3 x – 1 = 1
Point (2, 1)
Let change in x be 3 then change in ywillbe 4.
∴ Coordinate of y = 4 + 4 x – 1 = 0
∴ Point (3, 0)
Two points are (2, 1), (3, 0)

Question 3.
x₁, x₂, x₃, ……… and y₁, y₂, y₃, …….. are arithmetic sequences. Prove that all the points with coordinates in the sequence (x₁, y₁), (x₂, y₂), (x₃, y₃) ……… of number pairs are on the same line.
Answer:
If the line which contains the points (x₁, y₁), (x₃, y₃) also contains (x, y), then

Therefore, (x₁, y₁), (x₂, y₂) …………. will be in the same line

Question 4.
Prove that If the points (x₁, y₁), (x₂, y₂), (x₃, y₃) are on a single line, then the points (3x₁ + 2y₁, 3x₁ – 1y₁), (3x₂ + 2y₂, 3x₂ – 2y₂), (3x₃ + 2y₃, 3x₃ – 2y₃) are also on a single line. Would this be true if we take some other numbers instead of 3 and 2?
Answer:


Yes it is possible.

Textbook Page no: 231

Question 1.
Find the equation of the line joining (1, 2) and (2, 4). For points on this line with consecutive natural numbers 3, 4, 5, ……… as the x coordinates, what is the sequence of y coordinates?
Answer:
Equation of line joining the points (1, 2), (2, 4)

Question 2.
Find the equation of the line joining (–1, 3) and (2, 5). Prove that if the point (x, y) is on this line, so is the point (x+3, y+2).
Answer:

Question 3.
Prove that whatever number we take as, the point (x, 2x + 3) is a point on the line joining (–1, 1) and (2, 7).
Answer:

= \(\frac{2 x+3-7}{x-2}=\frac{2 x-4}{x-2}=2\)
The slopes are same hence die point (x, 2x+3) is passing through the points (–1, 1), (2, 7)

Question 4.
The x coordinate of a point on the slanted (blue) line is 3:
i. What it its y coordinates?
ii. What is the slope of the line?
iii. Write the equation of the line.

Answer:
As we get a right triangle on joining die three points’, with angles 30 : 60: 90 and ratio of their sides 1 : √3: 2

Question 5.
In the picture here, ABCD is a square. Prove that for any point on the diagonal BD, the sum of the x and coordinates is zero.

Answer:
B(2, -2), D(-2, 2) are the vertices of the diagonal BD: Sum of x,y coordinates of B = 2 + –2 = 0
Sum of x,y coordinates of D = –2 + 2 = 0
If (x, y)is a point on BD, then

Question 6.
Prove that for any point on the line intersecting the axes in the picture, the sum of the x and y coordinates is 3.

Answer:

∴ the sum of the and y coordinates of the point is 3.

Question 7.
Find the equation of the circle with center at the origin and radius 5. Write the coordinates of eight points on this circle.
Answer:
Equation of the circle
= (x – 0)² + (y – 0)² = 5²
= x² + y² = 25
x² = 25 – y²
x = \(=\sqrt{25-y^{2}}\)
y = 0 x = 5 (5, 0), (–5, 0)
y = 5 x = 0 (0, 5), (0, –5)
y = 3 x = 4 (4, 3), (4, 3)
y = 4 x = 3 (3, 4), (3, –4)
Coordinates of points on the circle
(5, 0), (–5, 0), (0, 5), (0, -5), (4, 3), (4, 3), (3, 4), (3, 4).

Question 8.
Prove that if (x, y) be a point on the circle with the line joining (0, 1) and (2, 3) as diameter, then x² + y² – 2x – 4y + 3 = 0. Find the coordinates of the points where this circle cuts they axis.
Answer:
As (0, 1), (2, 3) are the points joining the diameter of the circle, the center will be

Let (x, 0) be the coordinate which intersect
the x axis then, x² – 2x +3=0
\(x=\frac{2 \pm \sqrt{4-12}}{2}=\frac{2 \pm \sqrt{-8}}{2}\)
This circle can not be intersect the x axis. Let (0, y) be the coordinate which intersect the y axis then, y² – 4y + 3 = 0,
(y – 3)(y – 1) = 0 Coordinates are (0, 1) and (0, 3)

Question 9.
What is the equation of the circle shown here?

Answer:

Geometry and Algebra Orukkam Questions & Answers

Worksheet 1

Question 1.
If A(2, –1), B(3, 4), C(–2, 3) are the vertices of a triangle find the fourth vertex.
Answer:
Difference between x coordinates of A and B = 3 – 2 = 1, Coordinate of y = 4 + 1 = 5
x coordinates of D = –2 – 1 = -3
y coordinates of D = 3 – 5 = –2
Coordinates of D = (–3, –2)

Question 2.
In triangle ABC (4, 2) is the midpoint of AB. The midpoint of BC is (5, 4), the midpoint of AC is (3, 3). Find the vertices of the triangle.
Answer:

2x² = 12
∴ x² = 6
∴ y² = 3
From(1) y₁ = 4 – 3 = 1
x = 8 – 6 = 2, y₃ = 6 – 1 = 5
From(3) x₃ = 6 – 2 = 4 ,
Coordinates of A, B and C A(2, 1), B(6, 3), C(4, 5)

Question 3.
If A(2, –2), B(14, 10), C(11, 13) are the three vertices of a parallelogram ABC D write the coordinates of the fourth vertex
Answer:
A(2, –2), B(14, 10), C(11, 13).
Difference of x coordinates of A and B = 14 – 2 = 12.
x coordinate of D = 11 – 12 = 1.
Difference of y coordinates of A and B= 10 – (–2) = 12
y coordinates of D =13 – 12 = 1
Coordinates of D = (–1, 1)

Worksheet 2

Question 4.
Find the coordinates of the point which divides the line joining(4, –3), (9, 7) in the
Answer:

Question 5.
Find the coordinates of the midpoint of the line joining the points(1, –2), (–3, 4)
Answer:
Coordinates of midpoint =

Question 6.
The points A(6, 1), B(8, 2), C(9, 4), D(p, 3) are the vertices of a parallelogram. Find the value of p using the concept that the diagonals of a parallelogram bisect each other.
Answer:

The x coordinate of O using the concept that the diagonals of a parallelogram bisect

Question 7.
One end of the diameter of a circle is (1, 4). The center of the circle is (3, –4). Find the coordinates of other end
Answer:
One end of the diameter = (x₁, y₁) = (1, 4)
Center of the circle = (x, y) =(3, -4)
If other end of the diameter = (x₂, y₂)

Other end of the diameter (5 – 12)

Question 8.
Find the coordinates of the points P and Q which trisect the line joining (2, –3), and (4, –1) P,Q
Answer:

P can divide the line which joins the points (2, –3),(4, –1)in the ratio of 1 : 2

Question 9.
Prove thatA(6, 4), B(5, –2), C(7, –2) are the vertices of an isosceles triangle. If D is the midpoint of the side BC ,find the coordinates of D. Calculate the length of this median. Also, find the coordinates of centroid
Answer:

Worksheet 3

Question 10.
A-line makes an angle 45° with x-axis.Find the slope of the line
Answer:
Slope of the line = tan 45° = 1

Question 11.
The points on a line are (–1, 1), (3, 1), (5, 1)What is the angle made by this line with x-axis? What is the slope of this line
Answer:
This line is parallel to the x-axis so the slope is 0.

Question 12.
Find the slope of the line passing through (1, –3) (3, –5).
Answer:
Slope = \(\frac{-5+3}{3-1}=\frac{-2}{2}=1\)

Question 13.
A line passing through a point at a distance 4 from the right of origin on x-axis. If (3, –5) is a point on this line, find the equation of the line.
Answer:
Points are (4, 0) (3, –5)
Slope = \(\frac { -5 }{ -1 }\) = 5

Question 14.
If a line cut x-axis at (5, 0) and y-axis at (0, –3) Find the slope of the line given below.
Answer:
Slope of the line = \(\frac{-3-0}{0-5}=\frac{-3}{-5}=\frac{3}{5}\)

Question 15.
Find the slope of the line given below.

Answer:
Slope of the line = tan 60° = √3

Worksheet 4

Question 16.
Prove that the points (1, 3) (2, 5) (3, 7) are on a line
Answer:

Three points are lies on the same line.

Question 17.
The numbers in the sequence 2, 5, 8,11 and the numbers in the sequence 7, 11, 15, 19 …. are joined pairwise as given below(2, 7), (5, 11), (8, 15) Prove that these are on a line.
Answer:
Distance between (2, 7) and (5, 11) = \(=\sqrt{9+16}=5\)
Distance between (5, 11) and (8, 15) = \(=\sqrt{9+16}=5\)
Hence the distances are same, so the points are lie on the same line.

Question 18.
Find the slope of the line passing through (–2, 3) (5, 7) Write the slope of the fine parallel to it.
Answer:
Slope of the line which passing through the points (–2, 3) and (5, 7) = \(\frac{7-3}{5+2}=\frac{4}{7}\)
The line which joins the points (–2, 2) and (5, 6) is parallel to the first line.
Slope of the line which passes through the points (–2, 2) and (5, 6) = \(=\frac{6-2}{5+2}=\frac{4}{7}\)
Slope of the line which passes through the points (–7, 4) and (0, 8) = \(=\frac{8-4}{0+7}=\frac{4}{7}\)
The lines are parallel because their slopes are same.

Worksheet 6

Question 19.
Find the equation of the line passing through (5, 1), (1, –1), (11, 4)
Answer:
Equation of the line which passes through the points (5, 1), and (1, –1)

Equation is x – 2y – 3 = 0
Let find (11, 4) be on the equation 11 – 2 x 4 – 3 = 11 – 8 – 3 = 0
Equation is x – 2y – 3 = 0

Question 20.
(3, 0) is a point on the line joining the points (3x², 6x), (3y², 6y) then prove that xy = –1
Answer:
Slope of the line which passing through the points (3x², 6x) and (3y², 6y)

That is equal to the slope of the line which joins the points (3, 0) and (3x², 6x).

Worksheet 7

Question 21.
If a line is passing through (1, 1). This point divides the segment between axes in the ratio 3 : 4. Find the equation of this line.
Let consider the line 4x + 3y = 7, which cuts x axis at (a, 0) and y axis at (0, b)

Geometry and Algebra SCERT Questions & Answers

Question 22.
In the parallelogram ABCD A(2, 3); B(7, 3); and D(4, 7). Find the coordinates of C. [Score: 4, Time: 6 minutes]

Answer:
In the figure ΔAED, ΔBFC
AD = BC. DE = CF (1)
AE = BF = 2 unit (1)
∴ x coordinate of C
= 7 + BF = 7 + AE = 7 + 2 = 9 (1)
y coordinate of C = 3 + FC = 3 + ED = 3 + 4 = 7 (1)
C has the coordinates (9, 7)

Question 23.
In parallelogram ABCD A(2, 3); B(6, 5); and D(4, 7). Find the coordinates of C [Score: 4, Time: 6 minutes]

Answer:
Draw AE, DF parallel to x-axis. (1)
Draw BE, CF parallel to y-axis.
In right triangles Δ ABE, Δ DCF (1)
AB=DC, ∠BAE = ∠CDF
∠ABE = ∠DCF
∴ AE = DF= 6 – 2 = 4
BE = CF =5 – 3 = 2
x coordinate of C = 4 + DF = 4 + 4 = 8
y coordinate of C = 7 + CF = 7 + 2 = 9
Coordinates ofC (8, 9) (1)

Question 24.
In parallelogram ABCD A(x₁, y₁),B(x₃, y₂), D(x₂, y₃) Find the coordinates of C. [Score: 4, Time: 6 minutes]

Answer:
Draw AE, DF parallel to x-axis
Draw BE, CF parallel to y-axis
In right triangles ΔAEB, ΔDFE
AB=DC (1)
∠BAE = ∠CDF ∠ABE = ∠DCF
∴ AE = DF = x₂ – x₁ (1)
BE = CF = y₂ – y₁ (1)
x coordinate of C =
x₃ + DF = x₃ + x₂ -x,
y coordinate of C = y₃ + CF = y₃ + y₂ – y₁
∴ C has the coordinates =(x₂ + x₃ – x₁, y₂ + y₃ – y₃) (1)

Question 25.
Find the coordinates of the fourth vertex of the parallelogram shown here. [Score: 2, Time: 6 minutes]

Answer:
If A(x₁, y₁); B(x₃, y₂); D(x₂, y₃) are vertices of a parallelogram ABCD, then C has the coordinates (x₃ + x₂ – x₁, y₃ + y₂ – y₁) (1)
x coordinate of fourth vertex = 8 + 5 – 3 = 10
y coordinate of fourth vertex = 7 + 4 – 2 = 9
Coordinate of fourth vertex (10, 9) (1)

Question 26.
In the parallelogram PQRS, P(-3, 2) Q(2, 7), S(1, 9) are three vertices. Find the length of the diagonal PR. [Score: 4, Time: 6 minutes]

Answer:
x coordinate of R = 2 + 1 – (–3) = 6 (1)
y coordinate of R = 9 + 7 – 2 = 14 (1)
(6, 14) is the coordinate of R

Question 27.
A ABC A(6, 8); B(3, 4); C(–2, 2) are its vertices. The bisector of ∠A cuts BC at D.
a Find BD: CD.
b. Find the coordinates of D. [Score: 4, Time: 8 minutes]
Answer:

Question 28.
A circle is drawn with AB as diameter whose endpoints are A(3, 1) and 5(9, 10)
a. Find the coordinates of the center of the circle.
b. If another circle with diameter one-third of the above circle is drawn with the same center, what are the points that the circle cuts AB? [Score: 5, Time: 8 minute]
Answer:
a. Coordinates of the center OA

Geometry and Algebra Exam Oriented Questions and Answers

Short Answer Type Questions (Score 2)

Question 29.
Find the midpoint of the line segment joining the points(3, 0), (–1, 4).
Answer:
Mid point of the line segment joining the line segment joining the points (3, 0), (–1, 4).
\(=\left(\frac{3-1}{2}, \frac{0+4}{2}\right)=(1,2)\)

Question 30.
Find the equation of the line joining (1, 3), (2, 7).
Answer:
If (x, y) be any point on this line, then
\(\frac{(y-4)}{(x-1)}=2\)
y – 4 = 2(x – 1)
y – 4 = 2x – 2
2x + y + 2 = 0

Question 31.
What is the distance between the origin and the point (–2, -3)? What is the relation between this distance and the distance between the origin and the point (2, 3)?
Answer:
The distance to the points (–2,–3) is \(\sqrt{(-2)^{2}+(-3)^{2}}=\sqrt{13}\)
The distance to the points (2, 3) is \(\sqrt{2^{2}+3^{2}}=\sqrt{13}\)
Both the distances are equal.

Question 32.
Mark the points A(2, 3), 6(6, 6) by drawing the axes. Draw a rectangle with AB as di-agonal and sides are parallel to the axes. Find the coordinates of the other vertices of the rectangle. Find the length and breadth of the rectangle. Find the length of the diagonal AB.
Answer:
P(6, 3) Q(2, 6)
length = 4, breadth = 3
AB = \(\sqrt{4^{2}+3^{2}}-\sqrt{25} \div 5\)

Question 33.
What is the equation of the circle? Centre (2, 1), radius √5.
Answer:
Equation of the circle
(x – 2)² + (x – 1)² = 5
x₂ – 4x + 4 + y₂ – 2y + 1 = 5
x₂ + y₂ – 4x – 2y = 0

Question 34.
If (7, 3), (6, 1), (8, 2) and (p, 4) are the vertices of a parallelogram taken in order, then find the value of p.

Answer:
The midpoint of the diagonal AC and the diagonal BD coincide.

Question 35.
Find the equation of the line joining (–1, 3), (2, 5).
Answer:

Short Answer Type Questions (Score 3)

Question 36.
A is a point on the Y axis, equidistant from (3, 5) and (2, 6). Draw a rough sketch. If the Y co-ordinate of Ais P. What are the coordinates of A, in terms of P? Calculate the Value of P and hence the coordinates of A.
Answer:
The coordinate of A is (0, P). Since A is a point on the y-axis.

P2 – 12P + 40 = P2 – 10P +34
P2 – P2 – 12P + 10P = 34 – 40 – 2P = -6
P=3
∴ Coordinates of A are (0, 3)

Question 37.
The points A(0, 0), B(10, 0), C(5, 5√3 ) are the vertices of the triangle ABC. Find AB, BC, AC and prove that the triangle is equilateral.
Answer:
A(0, 0), B(10, 0), C (5, 5√3)
AB = 10 unit


AB = BC = AC
∴ ΔABC is equilateral

Question 38.
Prove that the points (2, 3), (7, 5), (9, 8), (4, 6) are the corners of a parallelogram.
Answer:

Since opposite sides are parallel, ABCD is a parallelogram.

Question 39.
a. What is the point at which the line 2x + 4y – 1 = 0 cuts the x-axis?
b. What about the y-axis?
Answer:
a. If the line 2x + 4y – 1 = o cut the x -axis at (x, 0), then 2x – 1 = 0
x = 1/2
The line intersect x axis is ( 1/2, 0 )
If the line 2x + 4y – 1 = 0 cut the y-axis at (0, y), then
4y – 1 = 0
y = 1/4
The line intersect y axis is (0, 1/4).

Long Answer Type Questions (Score 4)

Question 40.
Find the slope of the line joining (2, 3) and (3, –1). Check whether this line passes through the point (5, 6). What about the point (5, -9)?
Answer:

∴ Slope of the line joining (2, 3) and (3, –1)
\(=\frac{3-1}{2-3}=\frac{3+1}{-1}=-4\)
Slope of the line is –4
For point (5, –6)
Slope = \(\frac{6-3}{5-2}=\frac{3}{3}=1\)
Since slope = 4,
this line does not pass through(5,6)
For point (5, –9) Slope = \(\frac{-9-3}{5-2}=\frac{-12}{3}=-4\)
The line (5, –9) pass through the point.

Question 41.
Write the coordinates of each points on the lines 2x – y + 1 = 0 and 3x – 2y + 3 = 0. Find the co-ordinates of the point of intersection of the lines.
Answer:

Question 42.
a. Find the slope of the line joining the points (5, 3) and (4, 1).
b. Which are the points where this line meets x-axis and y-axis?
c. Write the coordinates of two other points on the line.
Answer:
a. Let (5, 3) = (x₁, y₁) and (4, 1) = (x₂, y₂),
= slop = \(\frac{y_{2}-y_{1}}{x_{2}-x_{1}}=\frac{1-3}{4-5}=\frac{-2}{-1}=\frac{2}{1}=2\)
b. If the line meets x axis at the point (x, 0), then slope = \(\frac{a-3}{x-5}=2 \Rightarrow 2(x-5)=-3\)
2x – 10 = –3,
2x = –3 + 10 = 7,
x = 7/2 = 3.5,
point is = (3.5, 0)
y axis \(\frac{y-3}{0-5}=2 \text { point }(0,-7)\)

c. slope is (2/1) means when x coordinate increase/decreases by 1, y co-ordinate increases decreases by 2. Another point on the line is (5 + 1), (3 + 2) = (6, 5)
A third point = (6 + 1) (5 + 2) = (7, 7)

Long Answer Type Questions (Score 5)

Question 43.
In the figure, the center of the circle is the origin and its radius is 1 unit. The points A,B are on the circle with ∠AOP = 30°, ∠AOB = 15°.
a. Find the coordinates of A and B.
b. Find the relation between the slope of the lines OA, OB and the tan measures of angles they make with the x-axis.
Answer:

Slopes of the lines and die tangent values-of the angles made by the lines with the axis are equal.

Question 44.
A circle is drawn with origin as the center and radius 10 units. Show that the point (–8, –6) is a point on the circle. Find out whether the point (9, –1) lies within the circle or outside the circle. Why?
Answer:
The distance between the centre and the point (-8,-6) is = \(=\sqrt{(-8)^{2}+(-6)^{2}}=\sqrt{100}=10\)
It is equal to the radius. So the point (-8, -6) is a point on the circle.
The distance between the centre, and the point (9,-1) is = \(\sqrt{9^{2}+(-1)^{2}}=\sqrt{81+1}=\sqrt{82}\)
√82 is smaller than 10.
So the point (9, –1) is a point inside the circle.

Geometry and Algebra Memory Map

Distance between (x_1,y₁) and (x₃, y₂) is \(\sqrt{\left(x_{2}-x_{1}\right)^{2}+\left(y_{2}-y_{1}\right)^{2}}\)
Distance of (x, y) from (0, 0) is \(\sqrt{x^{2}+y^{2}}\)

You can Download Electro Magnetic Induction Questions and Answers, Summary, Activity, Notes, Kerala Syllabus 10th Standard Physics Solutions Chapter 3 help you to revise complete Syllabus and score more marks in your examinations.

SSLC Physics Chapter 3 Electro Magnetic Induction Textbook Questions and Answers

SCERT Class 10th Standard Physics Chapter 3 Electro Magnetic Induction Solutions

Text Book Page No. 45

Sslc Physics Chapter 3 Kerala Syllabus Question 1.
You know that electrical energy can be converted into many other forms. Write down some examples.
Answer:

Text Book Page No. 46

Electromagnetic Induction Class 10 Kerala Syllabus Question 2.
Record your observations in the table given below.

Answer:

Text Book Page No. 47

Sslc Physics Chapter 3 Notes Kerala Syllabus Question 3.
Using magnet of high strength, and increasing the number of turns in the solenoid, the experiment is repeated. On the basis of the experiments complete the table (3.2).

Answer:

Physics Chapter 3 Class 10 Kerala Syllabus Question 4.
→ Why did the galvanometer needle deflect in the experiment?
Answer:
Whenever there is a change in the magnetic flux linked with a coil, an emf is induced in the coil.

→ Which were the instances in which there was a flow of current through the solenoid?
Answer:
Whenever there is a relative motion between the magnet and the solenoid, there is flow of electricity.

→ Which were the instances in which the current increased?
Answer:
Number of turns increased.Strong Magnet used Magnet / Solenoid moves with greater speed.

Text Book Page No. 48

Sslc Physics Chapter 3 Solutions Kerala Syllabus Question 5.
Observe the figure given below.
(The figure indicates the two stages of doing the experiment)

→ On which instance will the magnetic flux linked with the solenoid be less?
Answer:
Magnet is moved away from it solenoid.

→ On which instance will the magnetic flux linked with the solenoid be greater?
Answer:
When magnet is moved into the solenoid.

→ On which instance does a change in magnetic flux linked with the solenoid occur? (while it is moving/ while it is stationary)
Answer:
while it is moving.

Electromagnetic Induction Class 10 Questions And Answers Kerala Syllabus Question 6.
What may be the factors affecting the induced emf?
Answer:

• Number of turns of the coiled conductor.
• Magnetism.
• Movement of magnet and solenoid.

Class 10 Physics Chapter 3 Solutions Kerala Syllabus Question 7.
Which are the factors on which the direction of induced current in electromagnetic induction depend?
Answer:

• Direction of magnetic field
• Direction of conductor
• Direction of induced current

Text Book Page No. 49

Physics Chapter 3 Class 10 Kerala Syllabus Question 8.
Table 3.3

Answer:

Text Book Page No. 50

10th Physics Chapter 3 Kerala Syllabus Question 9.
The current obtained from the cell is unidirectional and is of the same magnitude. But what are the peculiarities of the current obtained by electromagnetic induction?
Answer:

• Direction changes.
• Magnitude changes.

Class 10 Physics Chapter 3 Kerala Syllabus Question 10.
We use mechanical energy in generators to move the magnet or coiled conductor continuously. In that case what shall be the energy change in a generator?
Answer:
Mechanical energy → Electrical energy

Class 10 Physics Chapter 3 Notes Pdf Kerala Syllabus Question 11.
Observe Fig 3.5(a) and write down the parts given in Fig. 3.5(b)

Answer:
ABCD: Armature.
B1, B2: Brush.
R1, R2: Slip rings.

Hsslive Guru 10th Physics Chapter 3 Kerala Syllabus Question 12.
ABCD indicates one turn of the armature coil. When the coil rotates about the axis in the clockwise direction, the portion AB moves upward and the portion CD moves downward.
Then according to the Fleming’s Right-Hand Rule.

→ What is the’direction of induced current in the portion AB? ( from A to B/ from B to A).
Answer:
from A to B.

→ What is the direction of induced current in the portion CD? (from C to D/from D to C).
Answer:
from C to D.

→ What is the direction of induced current in the coil ABCD? ( from A to D/from D to A).
Answer:
from A to D.

→ What is the direction of induced current in the external circuit? (through the galvanometer) (from B2 to B1/ from B1 to B2.
Answer:
from B2 to B1.

Class 10 Physics Chapter 3 Notes Kerala Syllabus Question 13.
What will be the positions of AB and CD when the armature completes 180° or one-half rotation?
Answer:
AB will be near the south pole of the magnet and CD will be near the north pole.

Physics 3rd Chapter Class 10 Kerala Syllabus Question 14.
Depict this stage of rotation of the armature in the science diary. At this instance,

→ What is the direction of movement of AB?
Answer:
Direction of AB is downward.

→ What is the direction of movement of CD?
Answer:
Direction of CD is upward.

→ What is the direction of current in the armature?
Answer:
from D to A.

→ What is the direction of current through the external circuit (through the galvanometer)?
Answer:
from B1 to B2.

Text Book Page No. 52

Kerala Syllabus 10th Standard Physics Chapter 3 Question 15.

Answer:

Text Book Page No. 52

Hss Live Physics 10th Chapter 3 Kerala Syllabus Question 16.
When 50 Hz AC is used, how many times will the direction of current change in the circuit?
Answer:
100 times.

Electromagnetic Induction Hsslive Kerala Syllabus Question 17.
Current is induced when the armature of a generator rotates. Slip rings and brushes are the ways and means by which this current is brought to the outer circuit. Is this arrangement necessary if the magnet in generator is made to rotate?
Answer: No

Hss Live Guru 10th Physics Kerala Syllabus Question 18.
Record in your science diary, the other ways by which mechanical energy can be made available for the working of a generator.
Answer:
From coal, naphtha, water from dam, exciters and big batteries. Field magnets are used as electromagnets. Mechanical energy also obtained from heat released by nuclear fusion.

Sslc Physics Chapter 3 Notes Pdf Kerala Syllabus Question 19.
Now write down in your science diary how the power for operating the generator which Babu saw near the stage was generated.
Answer:
The device which converts mechanical energy into electrical energy. When the armature rotates on its axis in the magnetic field, the magnetic flux linked within the coil changes. As a result, current is induced in the coil.

Sslc Physics 3rd Chapter Notes Kerala Syllabus Question 20.
Is it possible to produce DC (Direct Current) using a generator?
Answer:
Possible. If split-ring commutator is used in a generator instead of slip rings, we will get DC.

Text Book Page No. 54

Hsslive Guru 10th Physics Kerala Syllabus Question 21.
What are the similarities between the DC motor that we saw in the previous chapter and a DC generator?
Answer:

• Permanent magnet.
• Armature.
• Brushes.

Physics 10th Class Chapter 3 Kerala Syllabus Question 22.
Connect the output of a small DC generator to a galvanometer and rotate the armature continuously.

→ How is the needle deflected?
Answer:
Same direction.

→ Is the direction of current changing?
Answer:
No.

→ Is the magnitude of current the same?
Answer:
No. emf increases and decreases.

Physics Class 10 Chapter 3 Kerala Syllabus Question 23.

Answer:


Text Book Page No. 55

Physics Class 10 Chapter 3 Notes Kerala Syllabus Question 24.
Turn on & turn off the switch continuously. What do you observe?
Answer:
Bulb glows and then goes off.

Physics Class 10 Chapter 3 Kerala Syllabus Kerala Syllabus Question 25.
If the switch is kept in the on position what do you observe?
Answer:
Bulb does not glow continuously.

Question 26.
On what occasions do the flux change?
Answer:
When the switch is made to go on or off continuously.

Question 27.
What are the occasions when current flows through the second coil?
Answer:
When the switch in the first coil is kept on or off.

Question 28.
Can you suggest a method by which change can be brought in magnetic flux without switching on and off continuously?
Answer:
If AC is given to the primary coil instead of j DC, emf will be continuously induced in the secondary coil.

Text Book Page No. 56

Question 29.
Examine the diagrams of step up and stepdown transformers and list out the differences in their designs.
Answer:

Text Book Page No. 57

Question 30.

Answer:

Question 31.
A transformer working on a 240 V AC supplies a voltage of 8 V to an electric bell in the circuit. The number of turns in the primary coil is 4800. Calculate the number of turns in the secondary coil.
Answer:
V_p = 240V
V_s = 8V
N_p = 4800
\(\begin{array}{l}{\frac{V_{s}}{V_{p}}=\frac{N_{s}}{N_{p}}} \\ {N_{s}=\frac{V_{s} \times N_{p}}{V_{p}}=\frac{8 \times 4800}{240}=160}\end{array}\)

Question 32.
The input voltage of a transformer is 240V AC. There are 80 turns in the secondary coil and 800 turns in the primary. What is the output voltage of the transformer?
Answer:
V_p = 240V
N_s = 80
N_p = 800
\(\begin{array}{l}{\frac{V_{s}}{V_{p}}=\frac{N_{s}}{N_{p}}} \\ {V_{s}=\frac{N_{s} \times V_{P}}{N_{p}}=\frac{80 \times 240}{800}=24 \mathrm{V}}\end{array}\)

Question 33.
If voltage and current are known, what is the formula for finding power?
Answer:
Power = Voltage x Current

Text Book Page No. 58

Question 34.
In a transformer, if the voltage of the primary is V_p and the current in the primary is I_p, voltage in the secondary is V_s and the current I_s, write down the formulae connecting them.
Answer:
Power in the primary = V_p x I_p
Power in the secondary = V_s x I_s

Question 35.
In a transformer without any loss in power, there are 5000 turns in the primary and 250 turns in the secondary. The primary voltage is 120 V and the primary current is 0.1 A. Find the voltage and current in the secondary.
Answer:
N_p = 5000
N_s = 250
V_p = 120
I_p = 0.1A

Question 36.
Categorize the following relations appropriately as step up or step down transformers.

Answer:

Question 37.
As a result of the flow of current through a solenoid, is there any chance of inducing an electric current in the same solenoid?
Answer:
Yes. By self-induction.

Text Book Page No. 59

Question 38.

→ In which circuit does the bulb give a light with low intensity?
Answer:
Second circuit

→ Why does the intensity of light de-crease in that circuit?
Answer:
Back emf more

→ In which circuit is a magnetic field developed around the solenoid?
Answer:
On both circuits

→ If so in which circuit is a continuous emf induced?
Answer:
On second circuit

→ Have you understood the reason behind the decrease in the intensity of light in the second circuit? Write it down in the science diary.
Answer:
When AC passes through a solenoid, a changing magnetic field is generated around it. Due to this, an induced emf is generated inside the solenoid. This induced emf is in a direction opposite to that applied on the coil. Hence this is a back emf. This back emf reduces the effective voltage in the circuit.

Text Book Page No. 60

Question 39.
Inductors are widely used in AC circuits. Why?
Answer:
Inductors are used in the electronic circuits, to control and decrease current without power loss.

Question 40.
If resistors are used instead of inductors, what will be the disadvantage?
Answer:
Electric energy is lost in the form of heat.

Question 41.
Inductors are not used in DC circuits. Find out the reason and write it down in the science diary.
Answer:
Back emf is not produced as the flux formed by the current has no variation. So current control by inductor in DC is not possible.

Question 42.
Which are the main parts of a moving coil microphone?
Answer:
Diaphragm, Permanent magnet and Voice coil.

Question 43.
Which is the moving part in it?
Answer:
Diaphragm and Voice coil.

Question 44.
If a sound is produced in front of a movable diaphragm, what will happen to the diaphragm?
Answer:
Vibrates corresponding to the sound signals.

Question 45.
What happens to the voice coil then?
Answer:
Vibrates.

Question 46.
What will be the result?
Answer:
Creates electric signal corresponding to the sound.

Text Book Page No. 61

Question 47.
Find out the similarities and differences between a moving coil microphone and a moving coil loudspeaker and write them down in the science diary.
Answer:
Similarities:

• Both have voice coil.
• Have permanent magnet.
• Have diaphram.

Differences:

• Loudspeaker:
  Electrical energy → sound energy.
• Microphone:
  Sound energy → Electrical energy.

Question 48.
What is the energy transformation that takes place in a moving coil microphone?
Answer:
Sound energy → Electrical energy.

Text Book Page No. 62

Question 49.
How do we get mechanical energy for such generators?
Answer:

• Water from dam.
• Nuclear energy.
• Heat produced during the combustion of Naphta, Coal, Lignite ….etc

Question 50.
Write down the name of some power stations in Kerala.
Answer:

• Idukki – Moolamattom.
• Idukki – Pallivasal.
• Alappuzha – Kayamkulam.

Question 51.
Heat is generated in accordance with the equation H = I2Rt. In that case

→ What are the methods to reduce the heat generated?
Answer:

• Reduce current.
• Reduce resistance.
• Reduce the time taken.

→ If current (I) is reduced to half, how much will be the reduction in heat? (half, one fourth)
Answer:
one fourth.

→ If current (I) is reduced to 1/10 time show much will be the reduction in heat?
Answer:
1/100

→ How can we reduce the current without change in power? Find out on the basis of the equation P = V x I.
Answer:
by increasing voltage.

Text Book Page No. 63

Question 52.
→ What is the method to reduce the transmission loss?
Answer:
Power can be increased using a step-up transformer so that power loss can be minimized during power transmission.

→ Which type of transformer is there in a power station?
Answer:
Step-up transformer.

→ Which type of transformer is there in a substation?
Answer:
Step down transformer.

→ Which type of transformer is a distribution transformer?
Answer:
Step down transformer.

→ If a person standing on the earth touches a phase line, will she get an electric shock? Why?
Answer:
The person will get an electric shock because there is a potential difference (400V) between phase and earth.

→ Which are the lines essential for household electrification?
Answer:
Neutral, Phase and Earth lines.

Text Book Page No. 64

Question 53.
Analyze Fig.3.14 and find the answers to the questions given below.

→ To which device is the electric line reaching our home connected first?
Answer:
Watt-hour meter.

→ From where does the earth line start?
Answer:
From the main switch.

→ What is the use of a watt-hour meter?
Answer:
The electricity used is measured using a Watthour meter.

→ In which line are the fuses connected?
Answer:
Phase line.

→ What is the function of the main switch? Where is its position in the circuit?
Answer:
The electricity reaches the electrical appliances through the main switch. Therefore instead of turning each switch OFF, the main switch can be switched OFF. The main switch is placed just after the Watthour meter.

→ In the household electrical circuit, which is the third line, other than the phase and the neutral?
Answer:
Earth line.

→ What are the colors used for wires in phase, neutral and earth lines?
Answer:

• Phase – Red.
• Neutral – Black.
• Earth – Green.

→ Where is the earth wire connected in a three-pin socket?
Answer:
Pin E.

→ How are the household devices connected? Series/parallel.
Answer:
Parallel.

Question 54.
The advantages of connecting devices in parallel. Write them down.
Answer:

• Devices work according to the marked power.
• Devices can be controlled using switches as per need.
• The bulbs will get the required voltage.

Text Book Page No. 65

Question 55.
In a house, 5 CF lamps each of 20 W, works for 4hours, 4 fans each of 60 W work for 5 hours and a TV of 100 W works for 4 hours in a day. What will be the daily consumption shown by the watt-hour meter?
Answer:
4hour’s consumption of 5 CFL having 20 W
\(\frac { 5 × 20 × 4 }{ 1000 }\) = 0.4 kWh
5 hour’s consumption of 4 Fan having 60 W
\(\frac { 4 × 60 × 5 }{ 1000 }\) = 1.2 kWh
4 hour’s consumption of one T.V having 100 W
\(\frac { 1 × 100 × 4 }{ 1000 }\) = 0.4 kWh
Total unit = 2 kWh

Text Book Page No. 66

Question 56.
→ Which are the circumstances that lead to the flow of excess current in a house hold circuit?
Answer:
Over loading or Short circuit.

→ What happens to the circuit when there is an excess current in a circuit?
Answer:
More heat is generated. So appliances and circuit will get damaged.

→ How does a safety fuse protect a circuit?
Answer:
The current in the circuit may increase due to reasons such as short circuit, overload, excess flow of current or any problems in the insulation. As the higher temperature produced in the circuit due to these reasons makes the fuse wire to melt and the flow of current stops. Thus the circuit and the appliances are protected.

Text Book Page No. 67

Question 57.
What are the differences between ordinary fuse and MCB?
Answer:
Ordinary fuse works making use of heating effect of electricity while MCB works mak-ing use of heating and magnetic effects of electricity. The current in the circuit may increase due to reasons such as short circuit, overload, excess flow of current or any problems in the insulation.

As the higher temperature produced in the circuit due to these reasons makes the fuse wire to melt and the flow of current stops. Thus the circuit and the appliances are protected. MCB automatically breaks the circuit whenever there is an excess flow of current due to short circuit or overloading. After rectifying the circuit we can switch on the MCB and make the circuit as it was.

Question 58.
What is the advantage of MCB over a safety fuse?
Answer:
MCB is more sensitive to current than fuse, In case of MCB, the faulty zone of electrical circuit can be easily identified, With MCB it is very simple to resume to the supply, MCB is reusable and hence has less maintenance and replacement cost.

Question 59.
What is the function of ELCB/RCCB in the circuit?
Answer:
ELCB helps to break the circuit automatically whenever there is a current leak due to insulation failure or any other reason. Hence a person touching the electric circuit or a device does not get an electric shock. Nowadays RCCB, which ensures more safety than ELCB is made use of. In an ELCB one end of the relay coil is connected to the outer metallic cover and the other end is earthed.

If current leaks into the earth due to insulation failure or any other reason, a potential difference is developed between the ends of the relay coil. As a result, ELCB gets tripped off if the current exceeds a particular limit. This is with the help of a relay. In RCCB there is a provision to distinguish between the phase current and neutral current and to break the circuit if needed.

Question 60.
In the figure, which are the lines that are connected to the coil of the electric iron?

Answer:
Earth, Phase and Neutral lines.

Question 61.
If the phase line comes into contact with the body of the appliance due to defects in the insulation, what happens to the person who touches the body of the appliance?
Answer:
The person will get shock.

Question 62.
How can safety be ensured using a three-pin plug?
Answer:
The pin E of a three-pin plug comes into contact with the earth line. This pin is now connected to the body of the appliance. If the body comes into contact with an electrie connection, electricity flows to the earth through the earth wire. The flow of current to the earth through a circuit of low resistance increases the current. Hence heat generated in the fuse wire increases, the fuse wire melts and the circuit is broken. This will protect the instrument and the person handling it.

Question 63.
Which line comes into contact with the pin E.
Answer:
Earthline.

Question 64.
Howdoestheearth pin differs from the other pins? Why is it made different in this way?
Answer:
The earth pin is thick and long. As it is long it first comes in contact with the earth. Similarly, it loses the contact with the earth only at the end. As it is thick it offers less resistance. It carries more current than the amount of current coming from the phase.

Question 65.
Which part of the instrument is connected to the earth line?
Answer:
The earth line is connected to the metal casing of the electrical appliances.

Question 66.
Is TV working on AC or DC?
Answer:
on AC

Question 67.
We get DC from a mobile phone battery. But we use AC for charging it. What may be the reason?
Answer:
Most of the devices that work only on DC work by converting AC into DC. Mobile charger is a device that converts AC into DC.

Question 68.
Classify the devices known to you as those working in AC and DC.

Answer:

Text Book Page No. 71

One way switch:
Use to start/stop current flow and to change the direction of current flow.

Two-way switch:
Having two or more switches in different locations to control one electrical device.

Three-pin socket:
Electricity can be supplied to electrical appliances safely.

Ceiling rose:
Ceiling rose helps in that one live wire that is needed for ceiling light or fan to go in continuation.

ELCB:
Helps to break the circuit automatically whenever there is a current leak due to insulation failure or any other reason.

Regulator:
Automatically maintain a constant voltage level.

Indicator:
A device which provides visual or remote indication of a fault on the electric power system.

RCCB:
Distinguish between the phase current and neutral current and to break the circuit if needed.

MCB:
Automatically breaks the circuit whenever there is an excess flow of current due to short circuits or overloading.

Kit Kat Fuse:
Protecting a circuit against excess current.

Switchboard:
To control the flow of power.

Meter:
Instrument used to measure the magnitude of a quantity.

Main switch:
The main power supply of the RC models.

Bulb holder:
Holding a light bulb or lamp.

Clamp Ammeter:
The vector sum of the currents flowing in all the conductors passing through the probe.

Multimeter:
Can measure voltage, current, and resistance.

AC Voltmeter:
To measure the AC voltage across any two points of electric circuit.

Wire stripper:
Used to strip the electrical insulation from electric wires.

Screwdriver (*):
Tool, usually hand-operated, for turning screws with shaped slotted heads.

Screwdriver (-):
Tool, usually hand-operated, for turning screws with shaped slotted heads.

Tester:
Touched to the conductor being tested.

Plier:
For gripping something round like a pipe or rod, some are used for twisting wires.

Gloves:
Leather protector gloves – Worn over rubber insulating gloves to help provide the mechanical protection needed against cuts, abrasions and punctures.

Insulation tape:
To insulate electrical wires and other materials that conduct electricity.

Wire ( cable):
To carry electrical currents.

PVC Pipe fittings:
Used for plumbing and drainage.

PVC channel:
In Control Panels and Electrical Cabinets.

PVC Pipe:
Used as the insulation on electric wires.

Text Book Page No. 72

Question 69.
Construct such a circuit in aplywood as shown in Fig 3.19. The list of materials required and the number of items are given in the table.

Answer:

• Main switch.
• Fuse.
• MCB.
• Main fuse.
• Switchboard.
• ELCB.
• Fan.
• Bulb.

Electro-Magnetic Induction Let Us Assess

Question 1.
Write down the names of some devices that work based on the principle of electromagnetic induction.
Answer:

• Electric generator,
• Transformer,
• Moving coil galvanometer,
• Induction cooker etc.

Question 2.
What are the components essential for proving electromagnetic induction experimentally?
Answer:
Magnet, soft iron core connecting wire and Galvanometer.

Question 3.
Which are the factors that affect the induced emf in electromagnetic induction?
Answer:

• Number of turns in the armature.
• Strength of magnetic field.
• Speed of armature or field magnet.

Question 4.
Take a used cell from a calculator or remote control and connect it to a galvanometer as shown in the figure. What do you observe?

Answer:
The galvanometer needle deflects to one direction because there is a slight current flow.

Question 5.
Write down the names of DC sources.
Answer:
Cell battery, Solar cell, Generator, Thermocouple, etc.

Question 6.

a. Write down the names of parts numbered.
b. State the working principle of this device.
Answer:
a. 1. Field magnet,
2.Armature,
3. Slip rings.

b.Generators convert mechanical energy into electrical energy. Flux is changed and current is produced in the coil when the armature rotates from an axis. So current is induced due to flux change.

Question 7.
Write down the special features of AC and DC.
Answer:
Direct current (DC): Direction constant, emf increases and decreases.
Alternating current (AC): Direction changes continuously, emf increases and decreases.

Question 8.
Analyze the given graph and find out the instances at which the emf is maximum and minimum.

Answer:
Maximum: T/4, 3T/4
Minimum : 0, T/2, T

Question 9.
There is only one type of generator AC generator. Write down your responses about this statement.
Answer:
According to the nature of output, generators can be classified into 2 types AC generator and DC generator. Though ac current is produced in a DC generator with the help of split-ring commutator ac is converted into dc current.

Question 10.
Line diagrams of a generator are given.

a. What is the specialty of the electricity reaching the galvanometer if the armatures of both the generators are made to rotate?
b. What is the speciality of the electricity reaching the galvanometer if the field magnets of both the generators are made to rotate?
c. Draw the graphical representation of electricity obtained in both.
Answer:
a. DC in first and AC in second.
b. AC in both.

Question 11.
Electromagnetic induction is
a. charging a substance.
b. process of developing a magnetic field around a coil by passing electricity through a coil.
c. process of rotating the armature of a generator.
d. process of making electricity by the relative motion of a magnet or a coiled conductor.
Answer:
d. process of making electricity by the relative motion of a magnet or a coiled conductor.

Question 12.
Which is the device used to generate electricity?
a. generator.
b. galvanometer.
c. motor.
d. ammeter.
Answer:
a. generator.

Question 13.
Write down the similarities and differences in the structure of an AC generator and a DC generator.
Answer:
Similarities:

• Field magnet and Armature are present.
• Works on the principle of electromagnetic induction.
• AC produced on armature.

Differences:

Question 14.
A conductor hung horizontally in the north-south direction is connected to a galvanometer. The conductor is situated in a magnetic field acting in the East-west direction, In which direction should you move the conductor if maximum current is to be induced in the conductor in the north-south direction? Justify your answer.
a. towards east.
b. downwards.
c. upwards.
d. towards north.
Answer:
b. downwards. According to Fleming’s Right-hand rule.

Question 15.
Copper wires of the same length and thickness are connected to points A and B in all the three circuits. In-circuit (a) copper wire is not coiled. In circuits (b) and (c), the copper wire is coiled. Observe the circuits and answer the following questions.

a. When circuit (a) is switched on, what do you observe?
b.When circuit (b) is switched on, what change do you observe in the intensity of light? Justify your answer.
c. When circuit (c) is switched on, what change do you observe in the intensity of light? Justify your answer.
Answer:
a. Bulb glows.
b. No change in the intensity of light. There is no back emf produced as DC current is used in the circuit.
c. Intensity of light decreases. Back emf is produced in the circuit as A.C current flows through it and current is decreased.

Question 16.
The current in the secondary coil of a transformer is 1A and that in the primary is 0.5 A.
a. What type of transformer is this?
b.If 200 V is available in the secondary coil of this transformer, what is the voltage in the primary?
c. Explain the working principle of a transformer.
Answer:
a. Step down Transformer.

c.Mutual Induction:
Keep two sets of coils side by side. When the direction of current flow or its intensity is changed in one, the magnetic flux around it also changes. An emf and current is induced in the secondary coil. This phenomenon is called mutual induction.

Question 17.
In connection with the working of a microphone, a few statements are given inboxes. Arrange them in the proper sequence.

Answer:
Sound is produced → diaphragm vibrates → Voice coil vibrates → electrical signals are produced in the voice coil.

Question 18.
Thick insulated copper wires are used in the primary coil of a step-up transformer and in the secondary of a step-down transformer. What is the necessity of this?
Answer:
The power in the primary and secondary.of a transformer is equal. Current is more where voltage is less because P = VI. Thick wires are needed to flow more quantity of current. In the primary of step up and in the secondary of step down, quantity of current is more.

Question 19.
Which situation causes short circuit?
Answer:
When a phase and neutral comes into direct contact in a household circuit or when two-phase come in contact or when a phase and neutral comes into direct contact in a distribution line.

Question 20.
What is the role of earthing wire in a household circuit?
Answer:
The pin E of a three-pin plug comes into contact with the earth line. This pin is now connected to the body of the appliance. If at all the body comes into contact with an electric connection, electricity flows to the; earth through the earth wire.

The flow of current to the earth through a circuit of low resistance increases the current. As a result heat generated in the fuse wire increases and the circuit gets broken. This ensures the safety of instrument and the person handling it.

Question 21.
Why do we say that metallic devices should be earthed?
Answer:
Chances of electric shock are” more when metallic devices are used. When metallic devices are earthed, chances of electric shock can be prevented.

Question 22.
An electric heater calibrated 1.5 kW, 230 V is connected to a household branch circuit having 5 Afuse wire and is, made to work. What will happen?
Answer:
Current produced the circuit when the device works is
I = \(\frac { P }{ V }\) = \(\frac { 1500 }{ 230 }\) = 6.52 A
So 5 Amperage fuse bums.

Question 23.
Which are the devices connected in series in a household circuit?
Answer:
Fan, Switch, Regulator, etc.

Question 24.
What can be done to save electrical energy in schools and houses?
Answer:

• Use devices of good efficiency.
• Use electricity only when required.
• Reduce cooking using electricity.
• Reduce the use of air conditioners and refrigerators.
• Use LED bulbs instead of other bulbs.

Question 25.
Why do some mobile phones use three-pin plugs?
Answer:
In mobile phones, instead of earth pin, a plastic pin is used. For safety purpose, the phone neutral socket will have caps. Only if the pin enters the earth socket the other two sockets will open. It will be difficult to connect two-pin in such sockets. To solve this problem in mobile charges three-pin plug can be used.

Electro Magnetic Induction Extended Activities

Question 1.
Michael Faraday, the Father of electricity, did not even get elementary education. Are j you not inspired by the achievements of Faraday in the field of science? Conduct a seminar on “Contributions df Faraday and the hard work behind it.”
Answer:
Michael Faraday, an eminent scientist in the fields of physics and chemistry. He made his first invention in 1821. He proved that when a wire is kept in the magnetic field and current is passed through it, the wire moves.

By the series of experiments conducted in 1831 by using magnetic power Faraday found the important theory of production of current. He was called the father of electric current. He made valuable contributions in the field of chemistry also. It is wonderful to know that he didn’t get any formal education.

Question 2.
Energy is precious, especially electrical energy. Society must be convinced of the necessity of reducing the consumption of electrical energy. Prepare and propagate posters for this purpose.
Answer:

• Control the consumption of current, or else we will be in darkness.
• Next-generation also deserves current.
• Electricity is only for essential purpose.
• Use only efficient machinery to use minimum current.

Question 3.
Compare the induced current obtained when the armature coil rotates once in between the poles of a magnet, and the induced current obtained when the experiment using a magnet and coil was performed.
Answer:

Question 4.
Exhibit a model of electrical distribution network.
Answer:

Question 5.
Draw an electrical circuit containing the electrical appliances required for your classroom.
Answer:

Question 6.
How can the earthing be done in order to ensure safety in electrical circuits? Discuss and prepare a note.
Answer:
Overloading or short-circuiting may occur during the working of electrical devices due to some problems in the mains or within the circuit. The excess current produced is discharged to the ground through the earth wire. This is known as earthing.

Thus earthing provides safety in the electrical circuits. In household electrical circuits for the effective functioning of the earth wire, the earthing system should be proper.

• The pit in which the earth wire is placed should be filled with salt and coal.
• During summers it is required to wet the places where it is earthed.

Question 7.
Observe and record the meter reading in your house for 10 consecutive days. Based on this, find out the average consumption per day. Find out methods to reduce consumption and record them. Present your findings in the Energy Club.
Answer:
Average usage = \(\frac { Total usage }{ no.of days }\)
Methods to reduce the usage of electricity.

• Use devices of good efficiency.
• Use electricity only when required.
• Reduce cooking using electricity.
• Reduce the use of air conditioners and refrigerators.

Electro Magnetic Induction Orukkam Questions and Answers

Question 1.
Observe the figure.

a. Identify the device in figure 1?
b.What is Rj and Bj indicate in the figure?
c. What is the working principle of that device?
d. Identify the graph which indicate the emf produced by that device?
e. Suggest a way of method to increase the value of emf produced in armature coil of the device?
f. Which law is related with the direction of the induced emf in the armature? Explain?
g. Which part is used as rotor?
h.Which part is used as stator?
i. What are the advantages of armature used as stator?
j. Field magnets in power generator are electromagnet. Why?
k. Identify the device in figure 2?
l. Identify the graph given above of emf which is produced by that device?
m.What is the angle between the armature coils of a three-phase generator?
n. Some statements are given below which related to single-phase generator and three-phase generator. Classify them.
a. For each field magnet, there is only one armature.
b. There are three sets of armature coils for each field magnet.
c. AC generated in all the armature coils will be of the same phase at the same time.
d. AC generated in all the three armature coils will be of different phase at the same time.
Answer:
a. AC generator.
b. R1 – Slip Rings,
B1 – Brushes.
c. Electromagnetic Induction.
d. Graph 1.
e. Increase the number of turns.
f. Refer page no: 39
g. Field magnet.
h. Armature.
i. We can avoid rings and graphite brushes when the armature is used as stator. So there is no possibility of producing sparks.
j. Refer page no: 72 Question No: 1
k. Three-phase generator.
l. Graph 2.
m. 120°.
n. Single-phase generator – a, c.
Three phase-generator – b,d.

Question 2.
Observe the graph and answer the following.

a. In which angles are the rate of changes of flux is maximum?
b. In which angles are the induced emf maximum?
c. What is meant by period of AC?
d. What is meant by frequency of AC?
e. What is the aim of increasing number of magnetic pole and armature coil in a power generator?
Answer:
a. 90° and 270°
b. 90° and 270°
c. The time taken by the armature coil for a full rotation is called Period.
d. The number of cycles per second is the frequency of AC.
e. To increase the amount of electricity produced.

Question 3.
Observe the figures.

a. What kind of transformer is in figure 1?
b. What kind of transformer is in figure 2?
c. What is the working principle of a transformer?
d. Some statements are given below related to step-up transformer and step down transformer. Classify them. Number of turns in primary is less than secondary.

• Thick wires are used in secondary.
• Thick wires are used in primary.
• Voltage in secondary is high.
• Voltage in secondary is low.

e. Some relations are given about step-up transformer and stepdown transformer. Classify them.
Answer:
a. Step-up transformer.
b. Step down transformer.
C. Mutual induction.

Question 4.
Construct the circuit as in the figure. Observe the intensity of light when switch in the circuit is turn on.

a. What change is observed when 6V battery is connected instead of 6V AC in the circuit?
b. What change will occur in magnetic flux when 6V battery is connected to the circuit and 6V AC connected to the circuit?
c. What is the peculiarity of the induced emf when AC source is connected in the circuit instead of DC.
d. What is the name of this induced emf?
e. Name the phenomenon caused to reduce the intensity of light in the circuit.
f. What is the change in intensity of light will be occurred when soft iron core is inserted into the inductor?
g. What is the reason for the change in the intensity of light?
h. What is the phenomenon which caused to glow the LED?
i. Explain the phenomenon.
Answer:
a. Intensity of light decreases
b. When 6V AC is given, there is a change in the magnetic flux linked with the solenoid. Due to the change in flux, an induced emf is developed.
c. Emf will be in the opposite direction.
d. Back emf.
e. Self Induction.
f. Intensity of light decreases.
g. Change in flux increased.
h. Mutual Induction.
i. When the strength or direction of the current in one coil changes, the magnetic flux around it changes. As a result, an emf is induced in the secondary coil. This phenomenon is called Mutual induction.

Question 5.
Match the following related to ideas of different kind of power stations are given below.
Pallivasal, coal, Nuclear power station, Flowing water, Thermal power station. Kalpakam, Hydroelectric power station, Kayamkulam, Nuclear energy.
Answer:
Pallivasal :
Flowing water – Hydroelectric power station.

Kalpakam:
Nuclear energy – Nuclear power station

Kayamkulam:
Coal – Thermal power station.

Question 6.
There are some terms in connection with various power stations given. Fill in the blanks suitably.

Answer:
a. Nuclear Power station.
b. Kinetic energy.
c. Electrical energy.
d. Chemical energy.
e. Mechanical energy.
f. Heat energy.
g. Electrical energy.

Question 7.
Power stations are centers that generate and distribute large quantities of electricity. Power transmission is the process of sending electricity to distant places through wires from the power stations.
a. What is the voltage at which electricity is generated at the power station?
b. What is the voltage of electricity supplied for domestic consumption?
c. In which stage of power transmission is the step-up transformer used?
d. Which are the stages in which step down transformers are used in power transmission?
e. What are the problems arises during distant energy transmission?
f. What are the factors which depend when electricity passes through the conductor?
g. What are the methods to reduce the resistance?
h. What change will occur in power when intensity of current is reduced in the circuit?
i. How is it possible to reduce the intensity of current without power loss?
j. What will be the change in secondary current when secondary voltage of a step-up transformer is increased 10 times?
Answer:
a. 11 kV or 11000 V.
b. 230 V.
c. Phase I
d. Phase ii, iii, iv.
e. Voltage drop, Power loss.
f. Current, Resistance, Time.
g. Increase the thickness of the conductor.
h. Power decreases
i. Increase the voltage.
j. Become less by 1/10.

Question 8.
Step-up or Step down transformer in the power distribution system erected for the purpose of household distribution.
a. How many lines reach the input of the distribution transformer?
b.What is the potential of each phase line?
c. How many lines go out of the distribution transformer? Which are they?
d.Which method is adopted for connecting secondary coil in the distribution transformer?
e. Three-phase lines from output of distribution transformer are connected into a common point. What is the name of the common point?
f. What is the potential difference between a phase line and neutral line?
g. What is the potential difference between any two-phase line?
h.What is the potential difference between the earth and the neutral line?
i. What is the potential difference between a phase line and the earth line?
Answer:
a. 3 lines.
b. 400 V.
c. 4 lines come out, 3 phase and one neutral.
d.Star connection.
e. Neutral.
f. 230 V.
g. 400 V.
h.0 V.
i. 0 V.

Question 9.

a. How are the bulbs arranged in figure 1?
b. How are the bulbs arranged in figure 2?
c. Which circuits has more resistance?
d. All the switches in both the circuits may be turned on, in which circuit do the bulb give brighter light?
e. In which circuit current flowing through each bulb is maximum?
f. Which mode of connecting devices in your household electrical circuit is advisable?
Answer:
a. Series.
b. Parallel.
c. Series Connection.
d. Parallel Connection.
e. Parallel Connection.
f. Parallel Connection.

Electro Magnetic Induction Some more activities

Question 1.
Three-pin plug is used in the circuit of power devices like electric iron.
a. In three pin plug, what each pin indicate?
b. Which part of the device is connected to the earth pin?
Answer:
a. E-Earth line, N-Neutral line, P-Phase line.
b. To the body of the device.

Question 2.
What is the reason for massaging the body of a person who got electric shock?
Answer:
To increase the body temperature.

Electro Magnetic Induction SCERT Questions and Answers

Question 1.
Four identical solenoids and magnets are, depicted in the diagram. Magnets are shown as moving in the figures 1 and 2 and solenoids are shown as moving in figures 3 and 4.

a. Which are the figures showing inducing of emf? How?
b. Pair the pictures in which the galvanometer needle deflects in the same direction. What does the deflection indicate?
c. Draw the picture of a device that can produce continuous electricity using the same principle as shown above for producing electricity.
Explain its working.
Answer:
a. Emf will be induced in all the 4 coils in the diagrams; flux change happens in all the four activities.
b. Pairs (1) and (4), (2) and (3). deflection of galvanometer needle indicates the direction of the flow of current.

Question 2.
Certain factors that influence the induced emf in electromagnetic induction are listed below:
i. Increasing the speed of magnet.
ii. Decreasing the strength of magnet.
iii. Increasing the number of turns.
iv. Reducing the speed of rotation of the magnet.
v. Increasing the strength of magnetic field.
vi. Using solenoid with less number of turns.
Which of the above ideas can be used to get maximum emf by electromagnetic induction?
Answer:
i, iii, v.

Question 3.
The diagram shown below is an arrangement for producing 10V AC using electromagnetic induction. Observe the diagram carefully and answer the questions.

a. Which law is used to find out the direction of induced emf when the armature coil ABCD starts rotating?
b. In which direction the side CD should move (up/down) to produce a flow of current from x to y? What should be the direction of movement of the side AB (up/down) to produce a flow of current in the same direction?
C. Find out the frequency by drawing a time emf graph if the armature completes 10 cycles in 5 seconds.
Answer:
a. Fleming s Right Hand Rule.
b.Upward, side AB moves down.

Question 4.
Parts of an AC generator are given below. Field magnet, Armature, Slip rings, Brush.
a. Explain the position of these parts in an AC generator.
b. Write down the functions of any two.
Answer:
a. Armature rotates in the magnetic field of the field magnet. Springs are soldered to the ends of armature coil, Graphite Brush is connected in such a way as to have constant contact with springs.
b. Armature – Generate emf.
Field magnet – creates magnetic flux.

Question 5.
The various stages of rotation of an armatures coil while completing one rotation in a magnetic field and the graph of the emf produced by the coil are shown below:

a. Select the appropriate points from the pictures m,n,o,p corresponding to the positions 1,2,3,4 and 5 in the graph.
b. Explain the scientific basis for the pairing.
c. Which two pictures show the maximum flux changes? Point out one difference between the two.
Answer:
a. 1-m, 2-0, 3-n, 4-p, 5m OR 1-n, 2-p, 3-m,4-0, 5-n
b. The change in direction and intensity of magnetic flux in armature file.
c. n and o. Magnetic flux change takes place in the opposite directions in these two.

Question 6.
Maximum voltage produced in an AC generator completing 60 cycles in 30 seconds is 250 V.
a. What is the period of the armature?
b. How many cycles are completed in T/2 seconds?
c. What is the maximum emf produced when the armature completes 1800 rotation?
Answer:
a. Period = Time taken to complete one full rotation.
Period = \(\frac { Time taken for rotation }{ Number of rotations }\) = \(\frac { 30 }{ 60 }\) = \(\frac { 1 }{ 2 }\) = 0.5s
When the Armature ABCD rotates, change in the magnetic flux depends on its direction and intensity.
b. only \(\frac { 1 }{ 4 }\) of a rotation. T \(\frac { 1 }{ 2 }\),\(\frac { T }{ 2 }\),\(\frac { 1 }{ 4 }\)
c. 250V

Question 7.
In single-phase generators armature functions as rotor whereas in power generators armature functions as stator.
a. List out the other differences between single-phase and three-phase generators?
b. What are the advantages of using armature as stator in power generators?
Answer:
a.

b.

• Can increase the no.of turns of the armature coil.
• Can avoid slip rings and also the subsequent sparks.

Question 8.
If a rotor in a power generator completes 3000 rotations in a minute.
a. Which type of AC is produced here, single-phase or three-phase?
b. What will be the frequency of the AC produced if a pair of magnetic poles are ) used in the generator?
c. What would be the time interval to produce the same emf in the two phases if j the rotor completes 20 rotations in a minute?
Answer:
a. Three phase AC
b. Frequency = \(\frac { 3000 }{ 1 × 60 }\) = 50Hz
c. 20 rotations in a minute -3 seconds for completing one rotation. So the time interval to produce same emf is 1 second.

Question 9.

a. Observe the picture and identify the parts labeled as a, b, and c in the picture shown.
b. What is the energy change taking place in a moving coil microphone? What are the roles of the parts a,b, and c?
c. Why is the output signal of a moving coil microphone sent to the loudspeaker only after feeding it directly into an amplifier?
Answer:
a.1. Diaphragm.
2. Permanent magnet.
3. Voice coil.
b.
Mechanical energy to electrical energy Diaphragm – Vibrates in accordance with the sound falling on it.
Permanant magnet – Creates a magnetic field.
Voice coil – Creates electric signals corresponding to the sound.
c. The weak signals obtained from the microphone are strengthened by an amplifier.

Question 10.
Coils wound around a soft iron core connects two bulbs, B1 and B2 of 6 V. Analyse the figure and answer the questions.

a. If 6 V, DC is given in the coil A and the switch is on, which of the bulbs, B, & B2 will glow? Why?
b. If AC is given to the coil A instead of DC, which of the bulbs will glow B1 or B2?
c. Was there any variation in the brightness of Bulb B1 when AC and DC were supplied? Why?
d. Write down the names of two instruments that use the principle of mutual induction.
Answer:
a. Only B1 because electricity flows only through B1
b. B1 and B2 because of mutual induction.
c. Light of B1 will be reduced when AC is passed through it. This is due to the back emf produced due to self-induction.
d. Transformer, Relay switch.

Question 11.

Two solenoids A and B made of insulated copper wire are shown in the diagram. Observe the diagram and answer the questions below:
a. Write down different methods to light up the bulb connected in the coil B using the principle of electromagnetic induction.
b. What is the scientific principle applied to light up the bulb B?
Answer:
a.i. Switching S1 on and off by giving a DC supply.
ii. Keeping switched on after giving AC supply to the coil A.
iii.When coil A is moved relatively after supplying DC.
b. Mutual induction.

Question 12.
A transformer without power loss carries 4000 turns in the primary and 2000 turns in the secondary. If the primary voltage is 120 V and the current is 0.2 A.
a. What is the output voltage of transformer?
b. What is the current in the secondary?
c. What is the maximum output power?
d. Where are the thick wires to be used in this transformer in the primary or secondary? Why?
Answer:

d. In the secondary. Since P = V1 current is more in the secondary.

Question 13.
In a step up transformer, primary power is 50 W and output voltage is 100 V. If the current in the primary is 1 A.
a. What is the primary voltage?
b. What will be the current in the second ary?
c. \(\frac { Secondary power }{ Primary power }\) =
Answer:
a. P = V_p × I_p
500 W = V_p × 1A, V_p = 500 V
b. I_s = \(\frac { I_p × V_p }{ V_s }\) = \(\frac { 1 × 500 }{ 100 }\) = 5A
c. Primary and secondary powers are equal
\(\frac { Secondary power }{ Primary power }\) = 1

Question 14.
Power Station A :
Potential energy → Kinetic energy → Mechanical energy → Electrical energy.
Power Station B :
Chemical energy → Heat energy → Mechanical energy → Electrical energy.
Power Station C :
Nuclear energy → Heat energy → Mechanical energy → Electrical energy.
a. Identify the above power stations A, B, and C based on the energy change taking place in them.
b. Write down the merits and demerits of the power stations A, B, and C.
c. Name other three energy sources that can be used instead of these.
Answer:
a. A- Hydroelectric power station.
B- Thermal power station.
C- Nuclear power station.

b.1. Merits: No pollution, Energy of waterfall is used.
Demerits: Deforestation, Extinction of rare species of flora and fauna.

2. Merits: less area needed, danger possibility is less.
Demerits: Pollution, High consumption of fossil fuels.

3. Merits: Energy production on large scale, Less area needed.
Demerits: Pollution, Problems of radiation.

c. (1) Solar energy.
(2) Tidal energy.
(3) Windmills.

Question 15.
Names of power stations and statements related to them are given below in two groups. Match them suitably.
A. (1) Uses the energy of water stored at a height.
(2) Uses the heat generated by the burning of fuels.
(3) Uses nuclear energy.
B. (a) Pallivasal Power Station.
(b) Ramagundam Power Station.
(c) Kalpaklcam Power Station.
Answer:
a – 1,
b – 2,
c – 3.

Question 16.
Different stages of power production and transmission are given. Arrange them in the proper sequence.
a. Distribution transformer reduces the voltage from 11 kV to 230 V.
b. Voltage is reduced from 220 kV to 66 \ kV to supply electricity to large scale industries.
c. Turbine is rotated to operate the generator.
d. Transmission of electricity from the Power Station starts at 220 kV.
e. Electricity is produced at 11 kV.
f. Domestic consumers get electricity.
Answer:
c,
e,
d,
b,
a,
f.

Question 17.
Different stages of power transmission and distribution are given in a flow chart.

i. Choose the suitable terms from the bracket given below and arrange them in the given boxes in the correct order. (Power generator, substation, power transformer, star connection, distribution transformer, household connection, power grid)
ii. What do you mean by power grid? Give two advantages of power grid.
Answer:
i.
a. Power generator.
b. Power transformer.
c. Substation.
d. distribution transformer.
e. Star connection.
f. household connection.
ii. Power grid is the network that connects different power generating center and distribution systems to one another. Due to this arrangement, if any defect occurs either at the generator or transmission lines, electricity can be taken from any other power generating center through another set of transmission lines.

Question 18.
We use 230 V for our household purpose.
But the power produced at 11 kV is transmitted to distant places after increasing the voltage.
a. Why is electricity transmitted to distant places at high voltage?
b. Write down one disadvantage of transmitting electricity at high voltage.
c. What are the use of substations? Which type of transformer is used here?
Answer:
a. To reduce energy loss in the form of heat high voltage is used for long-distance transmission.
b. Transmission through populated areas is difficult. Transmission lines must be at a great height to ensure safety.
c. To reduce high transmission line voltage as and when required. Step down transformers are used for this purpose.

Question 19.
Power stations are centers where electricity is produced and distributed on a large scale.
a. What is the voltage of power production in our country?
b. Calculate the current if the power produced here in 11 MW.
Answer:
a. 11kV
b. p = VI
I = \(\frac { P }{ V }\) = \(\frac { 11 MV }{ 11 kV }\)

Question 20.
Identify the relation and fill up the blank.
Step up transformer: power transformer
Step down transformer:
Answer:
Distribution transformer.

Question 21.
Given diagram shows the star connection drawn by a child in his science diary.

a Can you draw a neutral line from the diagram? Why?
b.Draw the correct diagram of star connection.
Answer:
a. No: Three-phase lines do not meet at a single point.

Question 22.
Identical five bulbs of 230V and 40W are connected using star connection in the diagram given below.

a. What do you call the point N which is earthed in the circuit?
b. State the voltage differences between two phases and between a phase and neutral line in a star connection.
c. Which of the connected bulbs will glow? Why?
d. Two houses have electric connection from the same distribution transformer, but unfortunately one of the houses suffers power failure frequently; Explain it on the basis of household distribution.
Answer:
a. Neutral point.
b. 400 V in between two phases.
230 V in between a phase and neutral.
c. B4 glows because it is connected between the lines phase and neutral B, and B2 glows with low brightness. Each bulb gets 200 V as it is connected in series with 400 V.
d. Three phases in a transformer have separate fuses. So power supply problem in a line need not affect the other phases.

Question 23.
Examine the given circuits and answer the questions.

a. Identify series and parallel connection from the given circuits,
b. Parallel mode of connected devices is advisable for household electrification? Why?
Answer:
a. Figure A in series connection.
Figure B in parallel connection.
b. If the appliances are connected in parallel it will help to control each appliance with separate switches. It gives the needed voltage and current to appliances.

Question 24.
Four 60W, 230V bulbs are connected between a phase and a neutral as shown in the diagram. (Line voltage is 230 V)

a. How are the bulbs B, and B, are connected? What about B1 and B2?
b. Which bulb will glow at 60W power?
c. Which bulbs will glow with low power? Why?
d. Which bulbs in the circuit can be controlled using separate switches.
Answer:
a. B, and B, in series B₁ and B₂ in parallel.
b. B, and B₂.
c. B₃ and B₄ because each bulb gets less voltage as they are in series. So the bulb’s intensity will be less.
d. B₁ and B₂.

Question 25.
A flowchart of art household wiring is given in the diagram below. Fix the suitable devices in the space provided by picking from the given list.

(ELCB, MCB, Main switch, Watt-hour meter, Three-pin plug)
Answer:
(A) Main switch.
(B) ELCB.
(C) MCB.
(D) Three-pin plug.

Question 26.
We know that earth is an electron bank and that it has zero potential. But quite often we get electric shock from computer despite proper earthing.
a. Can electric shock from electric devices be avoided by earthing alone?
b. Proper earthing will give us safety from electric shock. What is meant by proper earthing? How can the earthing arrangement by done properly to ensure safety?
Answer:
a. No
b. Earth wire should carry all charge from the metal body of an electrical device to the earth effectively.

• Wire of suitable thickness must be used.
• Pits must be prepared to ensure effective earthing.
• Metal plates having large area as in plate earthing can be used.

Question 27.
Examine the diagram.

a. How would you connect the wires A, B and C from the electric iron to the wires of three-pin top correctly?
b.What is your response to the opinion that two pin top can be used instead of three-pin top in an electric iron?
Answer:
a. X wire is to be connected’ to earth pin. So connection should be made to be B. A and C must be connected to the wires Y and Z respectively.
b. Do not agree.
Insulation damage will carry electricity to the metallic part of electric iron. If one touches the metallic part he will get a electric shock. If the metallic part is earthed the charge will flow to the earth through the less resistance path.

Due to low resistance path the electric flow increases and the fuse burns out, thus safety is ensured or Agree. Special techniques are employed in new type iron boxes for avoiding shocks. Two pins shall be used only in such type appliances.

Question 28.
Which is the electric line to be connected to the point marked E in the diagram?

Answer:
The pin marked E must be connected to the earth line.

Question 29.
A bulb of 60W in a classroom remains switched on for a long time from 9 am to 5 pm due to the negligence of students in the class.
a. Calculate in joule the electric energy consumed by the bulb?
b. If similar negligence had happened in 3 classrooms, how many units of electric energy would have been wasted?
c. List out the different ways that can be adopted to save energy.
Answer:
a. Energy consumed =
= 60 x 8 x 60 x 60
= 1,728,000 J = 1728 KJ

b. Energy loss = \(\frac { 60 × 8 × 3 }{ 1000 }\) = 2.4 unit.

c.i. Avoid unnecessary use of lights and bulbs.
ii. Promote maximum use of natural light and wind.
iii. Use energy-efficient electrical appliances.
iv. Promote use of LED bulbs instead of filament lamps and CFL.

Question 30.
In a house 5 CF lamps each of 24 W work for a period of 5 hours and fans of 80W work for 5 hours.
a. What will be the electric consumption in kWh for a month?
b. Calculate the bill amount for one month by collecting the rate from the given table.

c. Find out the change in the monthly bill amount if CF lamps are replaced by LED lamps of 3W.
Answer:
a. One month’s consumption of energy by CFL
= \(\frac { 24 × 5 × 5 }{ 1000 }\) × 30 = 18 Unit
One month’s consumption of energy by
= \(\frac { 80 × 5 × 5 }{ 1000 }\) × 30 = 24 Unit
One month’s total consumtion of energy
= 18 + 24 = 42 Unit.
One months total bill amount
= 2.80 × 42 = Rs.118
c. One month’s total energy consumption by LED
= \(\frac { 3 × 5 × 5 }{ 1000 }\) × 30 = 2.25 Unit
2.25 + 24 = 26.25 Unit
One months bill amount
= 26.25 × 1.50
=Rs. 39.375 ≈ 40
Difference in bill amount
= 118 – 40 = 78

Electro Magnetic Induction Exam Oriented Questions and Answers

Very Short Answer Type Questions (Score 1)

Question 1.
Instead of permanent magnets, electromagnets are used as field magnets in power generators. Find out reasons from the following and write them down.
a. The strength of permanent magnets goes on decreasing.
b. The strength of electromagnets goes on decreasing.
c. Electromagnets can retain the required magnetic strength.
Answer:
a & c

Question 2.
Using the relation from the first pair, complete the other.
AC generator: slip rings
DC generator:
Answer:
Split rings.

Question 3.
Find the odd one in the group and write the reason.
[Voice coil, permanent magnet, slip rings, diaphragm]
Answer:
Slip rings. Others are parts of microphone.

Question 4.

Name the type of transformer.
Answer:
Step-up transformer.

Question 5.
What is the basic principle of working of a transformer?
Answer:
Mutual induction

Question 6.
A solenoid is connected to a galvanometer. A magnet is moved into and out of the solenoid frequently.

Which of the following will be most similar to the time emf graph of the electricity available from the solenoid.

Answer:
Figure 1

Question 7.
Using the relation from the first pair, complete the other.
AC generator: armature.
Moving coil galvanometer:
Answer:
Voice coil

Question 8.
Name the solenoid which is used to control emf.
Answer:
Inductor.

Question 9.
What is the number of turns 6f a secondary coil of a step-down transformer compared to primary?
(increasing, decreasing, doesn’t change)
Answer:
Increasing.

Question 10.
Which is used as rotor in the power generators?
Answer:
Field magnet.

Question 11.
Name the network which is connected in different power generating centers and distribution systems.
Answer:
Grid.

Question 12.
Using the relation from the first pair, complete the other.
Moolamattom – Hydroelectric power station
Kota –
Answer:
Nuclear power station

Question 13.
Find the odd one in the group and write the reason.
[Nuclear energy, Thermal energy, Kinetic energy, Electrical energy]
Answer:
Kinetic energy. Others are energy changes related to nuclear power stations.

Question 14.
What is the potential of the point where all the 3 phase lines are connected together?
Answer:
Zero potential.

Question 15.
What is the voltage of electricity supplied for domestic consumption?
a. 400 V
b. 250V
c. 230V
d. 50V
Answer:
230V

Question 16.
Using the relation from the first pair, complete the other.
Armature – Stator
Field magnet –
Answer:
Rotor.

Question 17.
The following diagram shows a three-pin Plug.

To which line is the fuse connected.
Answer:
The fuse is connected to the phase line.

Question 18.
In a household electric circuit. Where is the MCB (Miniature Circuit Breaker) connected?
Answer:
MCB is connected to the main fuse board.

Question 19.
Using the relation from the first pair, complete the other.
Hydroelectric power station flowing water Thermal power station –
Answer:
Steam at high pressure and temperature.

Question 20.
From given below, which device is used to measure electrical energy.
a. Transformer.
b. Watt-hour meter.
c. Three-pin plug.
d. Generator.
Answer:
b. Watt-hour meter.

Very Short Answer Type Questions (Score 2)

Question 21.
The figure shows a conductor PQ situated in a magnetic field, connected to circuit.

a. If the conductor is moved in the direction A, what is the direction of induced current?
b. State the rule used to find out the direction of induced current.
Answer:
a. from Q to P
b. Fleming’s right-hand rule. It states that hold the thumb, forefinger and middle finger of the right hand in mutually perpendicular direction, forefinger represents the direction of the magnetic field, middle finger represents the direction of current and thumb finger represents the direction of motion of the conductor.”

Question 22.
There are 10000 turns in the primary and 500 turns in the secondary of a transformer. The primary voltage is 240V and intensity of current in the primary is 0.1 A. Find the intensity of current if the secondary voltage is 12V?
Answer:

Question 23.
Match the following suitably.

Answer:

Question 24.
Arun decided to construct a transformer to change 240V to 12V.
a. Where does it need more number of turns in the primary or in the secondary?
b. Find the number of turns in the primary if 200 turns are used in the secondary.
Answer:
a. More number of turns are used in the primary.
B. \(\frac { Vs }{ Vp }\) = \(\frac { Ns }{ Np }\),
V_p = 240 V,
N_s = 200,
V_s = 12 V
N_p = \(\frac { Vp × Ns }{ Ns }\)
= \(\frac { 240 × 200 }{ 12 }\)
= 4000 Turns

Question 25.
Back e.m.f reduces the effective, voltage in the circuit. What is your opinion about this statement? Substantiate.
Answer:
When an AC passes through a solenoid, a changing magnetic field is generated around it. Due to this, an induced emf is generated inside the solenoid. This induced emf is in a direction opposite to the emf applied on the coil. Hence this is called back emf. Back e.m.f reduces the effective voltage in the circuit.

Question 26.
Arrange the following in given order.
Distribution transformer → Power generator → Substation → Power transformer
Answer:
Power generator → Power transformer → Substation → Distribution transformer.

Question 27.
In a household electric circuit
a. Where is the MCB (Miniature Circuit Breaker) connected?
b. What is the function of ELCB (Earth Leakage Circuit Breaker)
Answer:
a. MCB is connected to the main fuse board.
b. Prevents loss of. electricity through the circuits.

Question 28.
Write the voltages of the labeled parts a, b, c and d

Answer:
a. 11 KV
b. 220 KV
c. 11 KV
d. 230 V

Question 29.
Given is a schematic diagram of a household circuit which includes bulbs and a three-pin socket.

i. What does the dotted line represent?
ii. Which three parts are marked wrong in the diagram?
iii. Suggest methods to correct this.
Answer:
i. Earth line.
ii. 1. fuse is connected to the neutral
2. The switches S₁ and S₂ are connected to the neutral.
3. Three-pin socket is connected to the earth.

Very Short Answer Type Questions (Score 3)

Question 30.

Identify the device shown in the figure.

b. Suggest two methods to increase the emf obtained when such device work.
Answer:
a. ac generator
b. Increase the number of turns in the coil Use high strength magnets. Increase the speed of the motion of magnet.

Question 31.

a. Where is thick wire used in the primary or secondary?
b. Find the number of turns in the primary if there are 50 turns in the secondary coil?
Answer:
a. Secondary coil.
b. \(\frac { V_s }{ V_p }\) = \(\frac { N_s }{ N_p }\)
Primary Voltage V_p = 100 V
Secondary Voltage V_s = 10 V
No. of turns in the secondary (Ns) = 50
= \(\frac { 10s }{ 100p }\) = \(\frac { 50 }{ N_p }\)
N_p = \(\frac { V_p × N_s }{ V_s }\)
= \(\frac { 100 × 50 }{ 10 }\)
= 500 turns

Question 32.
Secondary coil is arranged near the primary coil both made up of insulated copper wire without touching on an iron core. A bulb is connected in the secondary coil. When an A.C was given in the primary it is found that the bulb glows.

i. How is current reached into the secondary coil from the primary even though they do not touch?
ii. Name the phenomenon.
Answer:
i. When an A.C flows through the primary coil a changing magnetic field is produced in it. This magnetic field induces a current in the secondary coil. So bulb in the secondary coil glows.,

ii. Mutual induction.

Question 33.
i. Which part produces magnetic field for the working of a generator?
ii. What is the function of the armature coil in the generator?
iii. Which parts in the A.C generator helps to reach current in the external circuit from the moving armature?
Answer:
i. Field magnet
ii. The armature coil cuts the magnetic flux lines and an induced emf is produced in the armature coil.
iii.Brushes and slip rings.

Question 34.
Convert 1 Kilowatt-hour of electric energy into Joules.
Answer:
1k Wh = 1000W × 1 hr
= 1000 W × 60 × 60 s = 3600000 Ws
= 3600000 J

Question 35.

Answer:
a. Hydroelectric power station.
b. Hydroelectric power station.
c. Water from dams.
d. Thermal power station.
e. Thermal power station.
f. Lignite.

Question 36.
Answer the following questions related to a three-pin plug.
a. How is the earth pin different from other pins?
b. In which of the three connecting wires should a switch be connected?
Answer:
a. The length and thickness of the earth pin is more than that of other pins. Since the length is more, when the three-pin is introduced into the socket, the earth pin comes into contact with the circuit first.
b. Phase wire.

Question 37.
a. Some energy sources are given below.
From them find out which source produces green energy.
i. Energy from fossil fuel.
ii. Nuclear energy.
iii.Solar energy.
iv.Energy from wind.
b. Write any two applications of green energy at the time of making of a house.
Answer:
a. Solar energy, Energy from wind
b. Avoid solar panels.
Use biogas plants.

Question 38.
In a household, there are 4 CFL’s of 15W each working for 5 hrs a day, 2 fans of 60W working for 5 hrs daily, 500W iron box working for 15 minutes a day. How many units of electricity is used in this house. What is the cost of electricity costing Rs.3 per unit?
Answer:
CFL Power =15 × 4 = 60 W,
time = 5hrs.
Fan Power = 60 × 2 = 120 W,
time = 5 hrs.
Iron box Power = 500 W,
time = 15 min = 1/4 hrs .
Energy in k Wh = (\(\frac { Power used in house }{ 1000 }\) ) × time
= 1.025
Electricity used per day= 1.025 kWh
Electricity used per month = 1.025 × 30
= 30.75 kWh
Cost of electricity at Rs.3 per unit = 30.75 × 3
= Rs.92.25

Very Short Answer Type Questions (Score 4)

Question 39.
i. What is the basic principle of working of a transformer?
ii. Write the function of a step up and a step-down transformer.
iii.Transformers work only in AC. They do not work in DC. why?
Answer:
i. Mutual induction
ii. A step-up transformer raises AC voltage. A step-down transformer decreases AC voltage.
iii. The direction of current flow is changed in AC. When AC flows through the primary, current is induced in the secondary due to mutual induction. There is no mutual induction in DC as its direction does not change. So a transformer cannot work in DC.

Question 40.

a. Write the observation when the switch is kept on and off continuously.
b. What can we do for getting light continuously?
c. Explain the process.
Answer:
a. Bulb will light only alternatively. When switch is in the ON position bulb will not light.
b. When an AC current is given in primary the primary coil its primary coil its magnetic flux around will continuously change and electricity is induced in the secondary coil.
c. Mutual Induction
If two coils are set apart and the electric current through one of the coil changes by its intensity or direction, the magnetic flux around it changes and an electricity is induced in the second coil. This phenomenon is called Mutual Induction.

Question 41.
An experiment is performed using a magnet and a coil of wire as shown in the figure.

a. From the following activities, find out the instants in which the galvanometer deflects.
i. The magnet is placed at rest inside the solenoid.
ii. Magnet is quickly inserted into the solenoid.
iii. The magnet is placed in the solenoid and then solenoid and the magnet are moved with the same speed in the same direction.
iv. The magnet is placed within the solenoid and the solenoid alone is moved to one side.
b.Write down the principle of the above observations.
Answer:
a. (ii) and (iv).
b. Electromagnetic induction.

Question 42.
Given below are the readings obtained from a transformer.

a. What type of transformer is this?
b. What is the principle of a transformer?
c. If power loss occurs, how much is it?
Answer:
a. Step-up transformer
b. Electromagnetic Induction
c. Power in the primary P = VI
= 150 × 1 = 150 W
Power in the secondary = VI
= 1000 × 1/10 = 100 W
Power loss = 150 – 100
= 50 W

Question 43.
a. A transformer working on a 240V AC supplies 12 V. The number of turns in the primary coil is 1000. Calculate the number of turns in the secondary coil.
b. In this transformer thick wire is used in which coil primary or secondary and what is the reason for it?
Answer:
a. \(\frac { V_s }{ V_p }\) = \(\frac { N_s }{ N_p }\)
V_s × V_p = N_s × N_p
V_s = 12 V
N_p = 1000
V_p = 240 V
N_s = V_s × \(\frac { V_s }{ V_p }\)
= 12 V × \(\frac { 1000 }{ 240 V }\)
= 50 turns
b. For maintaining same power.
Power = Voltage × Current Therefore if voltage is lower, thickness of the coil must be increased. Therefore thick wire is used in the secondary coil.

Question 44.
Kuttiadi, Kayamkulam, Kaiga, Kalpakkam, Mooiamattom
Some power stations in India shown in above.
a. Tabulate the above power stations according to the energy changes.
b. How does the electricity produced from Moolamattam power station?
c. Industrially electricity produced in the form of a.c. Why?
Answer:
a.

b.Water stored at a height is allowed to flow down a penstock pipe. The energy of flowing water is used to rotate the turbine and generate electricity.
c. It helps the transformer for rising and decreasing voltage.

Memory Map

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Kerala State Syllabus 9th Standard Social Science Part 1 Chapter 4 Medieval India: Concept of Kingship and Nature of Administration Questions and Answers

SSLC History Chapter 4 Notes

Medieval India Concept Of Kingship And Nature Of Administration 9th Question 1.
Discuss the characteristics of the sultanate administration based on the indicators given below.
1. Central administration
2. Local administration
3.Law of succession
4. Military administration
Answer:
Central administration:
The Sultanas implemented centralized rule in the administrative system. Let’s examine its important features.

• The influence of Turkish tradition
• The Sultan was the head of administration, military, and judiciary.
• There were different ministers and officers to assist the king in administration.
• An exact law of succession was absent.
• The leadership of the Caliphate of Baghdad was accepted.
• A strong army was maintained to defend the country from the threat of invasions and for the expansion of the empire.
• The vast country was divided into different regions for the convenience of administration.
• Regional laws prevailed at the village level.

Local Administration:

• For the convenience of administration, the empire was divided into provisions, shiqs, Parganas, and villages.
• Separate officers were appointed for each division. Their authority was not hereditary. The maintenance law and order, judicial administration, collection of taxes and organization of the army were the chief duties of these officers.
• They were under the direct control of the Sultan. But the Sultan did not directly intervene in the administration of the villages.

Low of succession:

• Sultan’s authority was not hereditary.
• The position of local officers was also not hereditary.

Military administration:

• Sultan was the head of the military force. The country was divided into different parts and these were entrusted with the nobles who were also the military commanders. These divisions were known as ‘Iqtas’ and their holders were known in different names as Iqtadar, Muqti, and Wali.
• The revenue collection and judicial administration of these divisions were the main duties of these Iqtadars.
• They were also duty-bound to maintain an army of their own.

Medieval India Concept Of Kingship And Nature Of Administration Notes 9th Question 2.
Examine the role of the market reforms in strengthening the military power during the Sultanate period.
Answer:
The Sultanate rule of Delhi was based on the strength of the army. The Sultans always paid attention to maintain a well-equipped army. Market regulation of Alauddin Khalji was a reform implemented with the intention of maintaining a large army with less expenditure. It was necessary to control the prices of essential commodities to reduce the military expenditure. As part of this, the government fixed the prices of essential commodities.

Hence the merchants were forced to sell their products at the fixed price. Black marketers and hoarders were strictly punished. The weights and measures were unified. The government established granaries to store the grains bought from the peasants. The corns were distributed during the time of famines at a moderate price. As a result, the soldiers were able to purchase commodities at a moderate price. Hence there was no need to pay them high salaries. Through these acts, the Sultan curtailed the military expenditure and the amount thus saved was utilized to enhance the strength of the army.

Medieval India Concept Of Kingship And Nature Of Administration Pdf 9th Question 3.
Prepare a note by discussing the common features of the Sultanate and the Mughal administrations.
Answer:
The features of the Mughal administration are pointed out below:

• Divine Right of Kingship
• The influence of Turkish and Mongal traditions.
• Powers centralized in the king. Based on military power
• Assistance of ministers and officials in the administration
• Existence of local administration.

Kerala Syllabus 9th Standard History Notes Question 4.
Akbar became successful as a ruler, acceptable to all through his administrative measures. Substantiate.
Answer:
The Mughal administration attained strength during the time of Akbar. As a ruler, his aim was to win the support of all sections of people. The policies adopted by Akbar for the same are given below:

• Adopted the title of Badsha-i-Hind (the Emperor of India)
• To maintain religious harmony he formulated a new faith Earned Din-i-llahi by inculcating the ideas of all religions.
• The Rajputs such as Raja Todarma, Birbal, Mansingh, etc. were appointed as high officials.
• Akbar and his relatives married Rajput ladies.
• The army was strengthened by including different sections.

9th Standard Social Science Notes Pdf Question 5.
To what extent Din-i-llahi formulated by Akbar was helpful in maintaining administrative stability and religious harmony? Analyze Up
Answer:
Akbarwanted to maintain peace, friendship and unity among different sections of people in his country. In order to have intellectual discourses, Akbar constructed the Ibadat Khana at his capital, Fatehpur Sikri. By inculcating the essence of all these discussions, he formulated the ideology of Din-i-llhai. It was a combination of ideas
and principles of different religions. He never compelled anyone to accept it. It did not have any rites, religious texts, places of worship or priests, except the joining function. Sulh-Kul or ‘Peace to alkl’ was its basic tenet.

Kerala Syllabus 9th Standard Social Science Guide Question 6.
Mansabdari System was introduced to strengthen the authority of the emperor. Substantiate.
Answer:
The base of Mughal administration was a strong military system. Instead of the military strength, the emperors needed the support of the nobles and officials for the maintenance and expansion of the empire. For this, Akbar adopted the Manasbdari system. The term ‘Mansab’ denotes the rank or position of Mughal military officer. Those who held this position were called Mansabdars.

The position of the officers, their salary and military responsibilities were categorically determined through the Mansabdari system. The rank of a Mansabdar was determined by the number of horses and cavalrymen he maintained. There were more than 30 ranks in the army of Akbar, ranging from mansabdars of 10 horses to 10,000 horses. Each Mansab had 2 sub-divisions called the ‘Zat’ and the ‘Sawar’ ‘Zat’ fixes the rank and salary of a person in the army while ‘Sawar’ refers to the number of horses a Mansabdar had to maintain

Hss Live Guru 9th Social Science Question 7.
What are the similarities and dissimilarities between the Iqta system of the Sultanate period and the Jagiradari system of the Mughar period?
Answer:
Jagirdari system was introduced by Mughal emperors to make the administration more effective. It was a higher form of the Iqta system of the Sultanate period. The following table explains the similarities and dissimilarities between the two systems.

Kerala Syllabus 9th Standard Social Science Notes Question 8.
Prepare a note comparing the village autonomy of the Cholas with that of the local self-government of present Kerala.
Answer:
For the sake of administration, the Chola kings divided the country into Mandalams, Valanadus, Nadus, and Kottams. A group of autonomous villages formed a Kottam. All the responsibilities and authorities relating to the administration of the villages were vested with the people of the villages. Two councils known as the Ur and the Sabha functioned for the purpose of village administration.

The people of the whole village was included in the Ur, whereas the Sabha was only a Council of the Brahmins. This system of administration has some similarities with the local self-government system of present Kerala. The center of authority in our system is Grama Sabha.

9th Standard Social Science Notes Question 9.
Prepare a note after comparing the portfolio of the Ashtapradhan council with that of the present-day ministers.
Answer:
The Maratha Administration:
You might be familiar the Maratha kingdom which ruled India in the 17^th century. Like all other medieval Indian rulers, the Maraths king was also the supreme authority with powers over the legislature, executive, judiciary and military. Observe the diagram which shows the functions of the minister in the council called Ashtapradhan.

If we observe the portfolio of the Ashtaparadhan Coun¬cil, we can understand that the present-day ministry also has all such portfolios.

9th Class Social Science Notes Question 10.
How did Maratha administration differ from the medieval administrative system? Discuss.
Answer:
The Maratha kingdom was divided into many parts for the convenience of administration. These divisions were provinces, districts (paranthas), Parganas and villages. The officers were directly appointed by the king. The country was further divided into two: ‘Swarajya’ and ‘Mogalai’. The Swarajya was the territories of the Marathas whereas the Mogalai was the regions annexed to the kingdom.

In addition to the land tax collected from the Maratha country (Swarajya) two kinds of taxes, Chauth and Sardeshmukhi, were collected form the annexed regions. During the medieval period, many fundamental changes occurred in the administrative system of The administrative system implemented by the medieval rulers influenced the later administrative systems considerably.

Social Notes For Class 9 State Syllabus Question 11.
Conduct a seminar on the various administrative systems that prevailed in medieval India.
Answer:
The features of various administrative systems that prevailed in medieval India are summarized as follows.

Let Us Assess

Kerala Syllabus 9th Standard Social Science Notes English Medium Question 12.
What were the circumstances that prompted the Sultans of Delhi to establish a centralized system of administration in India?
Answer:
The influence of Turkish tradition, the desire for expanding kingdom, need for maintaining military force were the circumstances that prompted the sultans of Delhi to establish a centralized system of administration in India.

9th Standard Social Science Notes Pdf In English Question 13.
Evaluate the characteristics of the Mansabdari system introduced by Akbar.
Answer:
The base of Mughal administration was a strong military system. Instead of the military strength, the emperors needed the support of the nobles and officials for the maintenance and expansion of the empire. For this, Akbar adopted the Manasbdari system. The term ‘Mansab’ denotes the rank or position of Mughal military officer. Those who held this position wre called Mansabdars.

The position of the officers, their salary and military responsibilities were categorically determined through the Mansabdari system. The rank of a Mansabdar was determined by the number of horses and cavalrymen he maintained. There were more than 30 ranks in the army of Akbar, ranging from mansabdars of 10 horses to 10,000 horses. Each Mansab had 2 sub-divisions called the ‘Zat’ and the ‘Sawar’ ‘Zat’ fixes the rank and salary of a person in the army while ‘Sawar’ refers to the number of horses a Mansabdar had to maintain.

9th Class History Notes Kerala Syllabus Question 14.
Match column ‘B’ with ‘A’ and arrange the table properly.

Answer:

Kerala Syllabus 9th Standard Geography Question 15.
Prepare a note on the Naynkara and the Ayyagar systems introduced during the Vijayanagara period.
Answer:
The central administration of the Vijayanagara empire was called Nayankara system and the local administration was called the Ayyagar system. The features of both these systems are discussed below.
i) The Navankara system:
The king was the head of the central administration of the Vijayanagara Empire. There were ministers and royal officers to assist the king in administration. There was only a small army under the direct control of the king. The provincial governors maintained fixed number of soldiers of their own. They provided the service of the army to the king whenever necessary. As they were also military heads, the king awarded them with the title of ‘Nayak’ along with a specific area of land. This system that prevailed at the center was known as the Nayankara system.
ii) The Avvaaar System:
For the convenience of administration, the empire was divided into provinces, nadus, and villages. Village was the basic unit. The village assemblies functioned in the same way as it did during the period of the Cholas. The day-to-day administration of the village was done by the officers known as ‘Ayyagars’ who inherited the post. This administrative system was known as Ayyangar System. The position of Ayyagars in the village administration was equal to that of the Nayaks in the central administration.

History Notes Class 9 Kerala Syllabus Question 16.
Prepare a short not on the Ashtapradhan Council of the Maratha period.
Answer:
Maratha kingdom ruled in India in the 17^th century. Maratha king was the supreme authority with powers over the legislature, executive, judiciary and military. Maratha’s ruler, Shivaji was assisted by the Ashtapradhan in his administration. Ashtapradhan was the council of ministers. Let us see the functions of ministers in the Ashtapradhan.

• Peshwa – Prime Minister
• Nyayadhyaksh – Chief Judicial officer
• Amatya – Finance officer
• Sachiv – Royal correspondence
• Mantrin – Private secretary of the king
• Pandila Rao – Religious and charitable activities
• Sumant – Foreign affairs
• Senapathy – Military

Medieval India: Concept of Kingship and Nature of Administration Model Questions and Answers

Kerala Syllabus 9th Std Social Science Notes Question 17.
Arrange the following in chronological order
1. Sayyid dynasty
2. Thuglaq dynasty
3. Lodi dynasty
4. Mamluk dynasty
5. Khalji dynasty
Answer:
1. Mamluk dynasty
2. Khalji dynasty
3. Thuglaq dynasty
4. Sayyid dynasty
5. Lodi dynasty

Kerala Syllabus 9th Standard History Question 18.
…………. was the capital of Sultanate.
Answer:
Delhi

9th Class Social Studies Notes State Syllabus Question 19.
Point out the important features of centralized rule implemented by the Sultans.
Answer:
The Sultanas implemented centralized rule in the administrative system. Let’s examine its important features.

• The influence of Turkish tradition
• The Sultan was the head of administration, military, and judiciary.
• There were different ministers and officers to assist the king in administration.
• An exact law of succession was absent.
• The leadership of the Caliphate of Baghdad was accepted.
• A strong army was maintained to defend the country from the threat of invasions and for the expansion of the empire.
• The vast country was divided into different regions for the convenience of administration.
• Regional laws prevailed at the village level.

Question 20.
What does the word ‘Sultanate’ refer to?
Answer:
The word Sultanate refers to the authority and suzerainty of one person over the others.

Question 21.
Complete the following:
1. Wazir – Revenue
2. Mamlik –
3. Chief sadr –
4. Divan-i-lasha –
Answer:
1. Wazir – Revenue
2. Mamlik – Military
3. Chief sadr – Judiciary
4. Divan-i-lasha – Royal correspondence

Question 22.
Construct a table showing local administrative divisions and their corresponding officers of the sultanate period.
Answer:

Question 23.
What were the duties of officers under Sultanate local administration?
Answer:

• Maintenance of law and order
• Judicial administration
• Collection of taxes
• Organisation of the army

Question 24.
Identify the main duties of Iqtadars
Answer:

• Revenue collection
• Judicial administration

Question 25.
Name the dynasties ruled the Vijayanagara empire.
Answer:

• Sangama
• Saluva
• Tuluva
• Aravidu

Question 26.
Mughal emperors of India were the successors ………. rulers
Answer:
Mongolian

Question 27.
Name the greatest ruler of the Mughal dynasty.
Answer:
Akbar

Question 28.
Prepare a note on the Mongal tradition.
Answer:
The foundation of Mongol tradition is in the concept that the king was selected for implementation the interests of the God. The Mongolian ruler Genghis Khan declared that he got the destiny of God through a revelation and hence he is following that path. The view that the king is the representative of God helped maintain the unquestioned authority of the king.

Question 29.
‘Akbarnama’was written by
Answer;
Abul Fazil

Question 30.
Who established the Mughal empire?
Answer;
Baburin 1526CE.

Question 31.
Observe the India map in page 58 of the textbook and identify the Subas of Akbar.
Answer:

1. Kabul
2. Lahore
3. Multan
4. Delhi
5. Agra
6. Ayodhya
7. Allahabad
8. Ajmir
9. Gujarat
10. Malwa
11. Bihar
12. Bengal
13. Khanudesh
14. Berar
15. Ahammadnagar
16. Orissa
17. Kashmir
18. Sindh

Question 32.
How was the rank of a Mansabdari determined?
Answer:
The rank of a Mansabdari was determined by the number of horses and cavalrymen he maintained.

Question 33.
Narrate the Naval supremacy of Chola kings
Answer:
The Chola kings organized a very strong army. They had the greatest naval power of that period. The Cholas extended their empire up to Malaysia, Indonesia, Ceylon, etc. The Bay of Bengal was known as the lake of the Cholas. All these achievements rural the naval supremacy of the Chola kings.

Question 34.
What has regulated the Chola administration?
Answer:
The Chola administration was regulated through Royal decrees.

Question 35.
Match the following.

Answer:

Question 36.
What as the most important feature of the Chola administration?
Answer:
Village autonomy

Question 37.
Identify the powers vested with the Sabha.
1. Receive land for the temples.
2. ……………
3. ……………
Answer:

• Receive land for the temples
• Collect tax by surveying land
• Undertake public works for the welfare of the people
• Keep accounts and records
• Conduct judicial administration of the village.

Question 38.
Complete the following

Answer:

• Nayankara system
• Ayyagas system

Question 39.
Match the following

Answer:

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Kerala State Syllabus 9th Standard Social Science Part 2 Chapter 5 Ocean and Man Questions and Answers

SSLC Geography Chapter 5 Notes

Ocean And Man Class 9 Kerala Syllabus Question 1.
Identify the location of each ocean from the world map. List the straits, bays and the seas of each ocean with the help of an atlas.
Answer:

Kerala Syllabus 9th Standard Social Science Notes Question 2.
The following table contains the names of some major islands and peninsulas in the world. With the help of an atlas find out the names of the oceans to which they below.
Answer:

1. Indian Ocean
2. Indian Ocean
3. Pacific Ocean
4. Atlantic Ocean
5. Atlantic Ocean

Kerala Syllabus 9th Standard Social Science Notes Pdf Question 3.
Complete the table using fig. 5.7 in textbook


Answer:

9th Standard Social Science Notes Pdf Kerala Syllabus Question 4.
The equatorial regions; record a high amount of salinity as compared to the polar regions why?
Answer:
The temperature is high in equatorial regions compared to polar regions. Density increases as temperature rises. High density is associated with high salinity. There is possibility of high evaporation in equatorial regions. That is why equatorial regions record high amount of salinity.

9th Standard Social Science Notes Kerala Syllabus  Question 5.
Why is salinity is less at river mouths?
Answer:
Salinity is less at river mouths because of huge amount of freshwater added from hundred of rivers.

9th Std Social Science Notes Kerala Syllabus Question 6.
Which are the warm and cold currents of the Atlantic Ocean? Identify the continents near which they flow.

Answer:

Kerala Syllabus 9th Standard Social Science Notes English Medium Question 7.
Complete the following table based on the currents of the Indian Ocean.


Answer:

Kerala Syllabus 9th Standard Social Science Notes Malayalam Medium Question 8.
You have learnt the uses of Oceans. Conduct a seminar on the topic ‘influence of Oceans in human life’.
Answer:
“Influence of Oceans in Human Life”
Oceans play significant role in the life of human beings. We cannot neglect oceans because oceans are useful in

• Influencing our climate.
• Providing mineral deposits.
• Helping power generation.
• Providing source of food.

We shall now explain the influence of Ocean in detail.
Climate:
Oceans have a decisive role in controlling the climate along the coastal regions. The sea breeze during the day and the land breeze in the night regulate the temperature over the coasts. Oceans play a part in the formation of weather phenomena like rain, wind, and cyclones. Generally, the coastal regions have moderate climate, whereas severe summer and winter prevail in regions away from the sea.
Oceans as a source of food:
Fish is an important item of food. Fishing is major
activity in Japan, Peru, China, Norway, and the United States of America. Marine organisms are the source of many medicines. They are used for the production of antibiotics, steroids, and vitamins.

Ocean and Man Model Questions and Answers

9th Standard Social Science Notes Pdf In English Kerala Syllabus Question 9.
Nearly ………… % of earth’s surface area is covered with water.
Answer:
71%

9th Class Social Science Textbook Kerala Syllabus Question 10.
Name the Oceans
Answer:
a) The Pacific Ocean
b) The Atlantic Ocean
c) The Indian Ocean
d) The Artie Ocean
e) The Antarctic Ocean

9th Standard Social Science Textbook Kerala Syllabus Question 11.
Match the following

Answer:

Kerala Syllabus 9th Standard Social Science English Medium Question 12.
Distinguish between bay and strait.
Answer:
The portion of the sea surrounded by land on three sides is called a bay. On the other hand, the narrow stretch of sea between two landmasses is known as strait.

Question 13.
Complete the table

Answer:

Question 14.
Define Peninsula
Answer:
The landmasses surrounded by sea on three sides are called peninsula.

Question 15.
Identify the important features of seawater.
Answer:

• Temperature
• Salinity
• Density

Question 16.
Where do you find the highest Ocean temperature?
Answer:
Between 10° latitudes on either side of the equator

Question 17.
As we more away from the equator, temperature considerably.
a) Increases
b) Decreases
c) First increases and then decreases
d) Remains constant
Answer:
a) Increases

Question 18.
What is the reason for the variation in temperature over different latitudinal zones?
Answer:
Variation in the amount of insolation received on the earth is the major reason, The Ocean currents and winds also influence the temperature of seawater.

Question 19.
Define Salinity?
Answer:
The concentration of salt content in seawater is known as salinity.

Question 20.
The average amount of saltiness of seawater is
a) 2.5%
b) 3.5%
c) 4.5%
d) 5.5%
Answer:
b) 3.5%

Question 21.
Name the major contents of seawater
Answer:

• Sodium chloride
• Magnesium chloride
• Magnesium Sulphate

Question 22.
Point out the conditions leading to variations in salinity.
Answer:

• Salinity will be more in landlocked seas.
• Salinity increases in areas of high evaporation.
• Salinity decreases in areas where snow meltwater reaches in large quantity.
• Salinity decreases at river mouths.
• Heavy rainfall leads to reduction in salinity.

Question 23.
What causes movements in seawater.
Answer:
The density of seawater is not uniform everywhere. This is due to the variations in salinity and temperature of sea water. Density decreases as temperature increases, and it increases as salinity increases. You have understood that the temperature, salinity and the density of seawater are not uniform everywhere. These variations lead to movements in seawater.

Question 24.
Which are the movements of seawater.
Answer:

• Waves
• Tides
• Ocean currents

Question 25.
What are sea waves?
Answer:
The up and down motion of the water along the surface of the sea is called sea waves.

Question 26.
Mark the missing portion.

Answer:

1. WaveLength
2. Crest
3. Wave height
4. Trough

Question 27.
Name the following:
(i) The summit of the wave
(ii) Bottom part of the wave
(iii) Distance between 2 adjacent crests
(iv) Vertical distance between the crest and the trough
Answer:
(i) Wave crest
(ii) Wave trough
(iii) Wavelength
(iv) Wave height

Question 28.
………. is the reason for waves.
Answer:
The friction exerted by winds on the ocean surface

Question 29.
As the speed of the wind increases, the strength of the wave
a) Decreases
b) Increases
c) Remains constant
Answer:
b) Increases

Question 30.
Name two damages caused by strong waves
Answer:

• Cyclones
• Shelving of shores

Question 31.
Some measures are taken to prevent damage and to protect the lives of people living in the coastal areas. Identify the measures.
Answer:

• Depositing boulders along the seashore.
• Construction of interlocking concrete structures (Pulimuttu)
• Planting of mangroves.

Question 32.
Name the sea waves generated by earthquakes and volcanos
Answer:
Seismic sea waves or tsunami waves.

Question 33.
Prepare a note on mud bank
Answer:
Mudbank is a phenomenon that develops in the Arabian Sea during the onset or the end of the monsoon season. Planktons grow luxuriantly in the turbulent muddy water along the seashore during the monsoon rains. Schools of fish such as shrimp, sardine, and mackerel arrive to feed on the planktons and the mud, giving fishermen a good catch. This phenomenon is known as mud bank.

Question 34.
What do you mean by tides?
Answer:
Tides are he periodic rise and fall of water level in the ocean.

Question 35.
Distinguish between high tide and low tide
Answer:
The rise in the level of ocean water is the high tide and the lowering of the water level is known as the low tide.

Question 36.
What are the reasons for tides?
Answer:
Tides are formed as a result of the gravitational pull exerted by the moon and the sun along with the centrifugal force due to the earth’s rotation.

Question 37.
‘ Illustrate with the help of a figure the occurrence of high tide and low tide.

Answer:
The water level on the part of the earth facing the moon rises. The rise in water level due to the gravitational pull exerted by the moon leads to high tide. You might have noticed that the water level at the opposite side also has risen. The centrifugal force due to the earth’s rotation is the reason for the rise in water level here. It can be seen that the water level goes down at places located 90° away from the places of tidal influence. This is due to the draining of water towards the tidal regions. The phenomenon of fall of water level is known as low tide.

Question 38.
Point out the important effects of tides.
Answer:
High tides and low tides have many effects. Let’s have a look at them.

• The debris dumped along the seashores and ports are washed off to the deep sea.
• The formation of deltas is disrupted due to strong tides.
• Brackish water can be collected in salt pans during high tides.
• The fishermen make use of the tides for going and returning from the sea in catamarans.
• Tidal energy can be used for power generation.
• Ships can be brought to shallow harbors during high tides.

Question 39.
Prepare a note on ocean currents
Answer:
It is a type of seawater movement. Ocean currents are the continuous flow of seawater from one direction to another. They can be classified as warm currents and cold currents. Warm currents are the currents that flow from the tropical or subtropical regions towards the polar or subpolar regions. The water that flows in will be warmer than the water at the destination.

Similarly, cold currents are the currents that flow in from the polar or the subpolar regions towards the tropical or subtropical regions.In this case, the water that flow in will be colder than the water at the destination. The temperature and salinity of seawater varies from ocean to ocean. This difference leads to density difference in seawater. The difference in density is one of the factors that cause ocean currents.

Question 40.
Complete the chart.

Answer:

1. Warm currents
2. Cold currents

Question 41.
What are the effects of ocean currents?
Answer;

• Influence the climate of coastal regions.
• Fog develops in the regions where warm and cold currents meet.
• The regions where the warm and cold currents meet provide favorable conditions for the growth of fish.

Question 42.
Which are the mineral deposits in ocean.
Answer;

• Iron ore
• Coal
• Petroleum
• Natural gas

Question 43
The oil field started in 1974 in Mumbai is known as
Answer:
Mumbai High

Question 44.
Name some countries where fishing is an important activity.
Answer:

• Japan
• Peru
• China
• Norway
• USA

Question 45.
What are the medicinal user of marine organisms?
Answer:
Marine organisms help in production of :-

• antibiotics
• steroids
• vitamines

Question 46.
Prepare a flow chart showing method of purifying seawater.
Answer:

Let Us Assess

Question 47.
Which among the following statements is not related to the Indian Ocean?
a. The southern part of this ocean extends up to the Antarctic Ocean.
b. The average depth is more than that of the Atlan tic Ocean.
c. The Puerto Rico trench is situated in this ocean.
d. It ranks third in area.
Answer:
B & C are not related

Question 48.
which among the following places record the least salinity? why?
1. Land-locked sea,
2. Areas of heavy rainfall
3. Areas of high evaporation
Answer;
Landlocked sea. Because salinity increases in landlocked seas.

Question 49.
Is there any relation between the intensity of waves and the wavelength? substantiate
Answer:
The Intensity of waves is defined as the power delivered per unit area. The unit of intensity will be W.m2. The wave energy comes from simple harmonic motion of its particles. The total energy will equal the maximum kinetic energy. As intensity of waves increases the wavelength also increases.

Question 50.
High tide occurs twice a day. Explain this statement.
Answer:
The rise in water level due to the gravitational pull exerted by the moon leads to high tide. Tides can occur as two high waters and two low water each day. The tides are occurred by the gravitational. The moon’s gravity pulls the ocean surface closer to it and the moon makes two trips around the earth each day. Hence there in high tide twice a day.

Question 51.
Explain spring tides and neap tides with the help of diagrams.

The sun, moon, and earth come in a straight line on full moon and new moon days. The tidal force will be intense due to the combined influence of sun and moon. As a result, the tides formed on these days will be stronger. These are known as spring tides. The moon and the sun will be at an angular distance of 90° from the earth after seven days from the full moon and new moon days. As the sun and the moon attract the earth from an angular distance of 90° the tides casued are weak. Such weak tides are known as neap tides. Note the positions of the earth, moon, and sun in the given diagram.

Question 52.
Oceans play an important role in human life and environment. Justify.
Answer:
Influence of Oceans in human life
Oceans play significant role in the life of human beings. We cannot neglect oceans because oceans are useful in

• Influencing our climate.
• Providing mineral deposits.
• helping power generation.
• Providing source of food.

We shall now explain the influence of ocean in detail.

You can Download Election and Democracy Questions and Answers, Summary, Activity, Notes, Kerala Syllabus 9th Standard Social Science Solutions Part 1 Chapter 8 help you to revise complete Syllabus and score more marks in your examinations.

Kerala State Syllabus 9th Standard Social Science Part 1 Chapter 8 Election and Democracy Questions and Answers

SSLC History Chapter 8 Notes

Kerala Syllabus 9th Standard Social Science Notes Pdf Question 1.
Elections are indespensible in a democracy. Substantiate.
Answer:
Elections are indispensable in a democracy due to the following reasons.

• Elections reflect the aspirations of the people.
• People can select the rulers of their choice through elections.
• People can participate and respond in democratic process.
• Election is a good reason for the rulers to act according to the aspirations of people.

9th Standard Social Science Notes Pdf Question 2.
Complete the Flow Chart.

Answer:

9th Standard Social Science Notes Pdf Malayalam Medium Question 3.
Narrate the procedure of simple majority system.
Answer:
According to this system, elections are held in the following manner.

• The country is divided into various electral districts known as constituencies.
• One representative is elected from one constituency.
• Any number of candidates can contest.
• The candidate who gets the highest number of votes is elected.

Kerala Syllabus 9th Standard Social Science Guide Question 4.
Proportional representation is adopted to elect
a) President
b) Vice president
c) Members of Rajya Sabha
d) All the above
Answer:
All the above

Kerala Syllabus 9th Standard Social Science Notes Malayalam Medium Question 5.
Match the following

Answer:

9th Standard Social Science Notes Pdf In English Medium Question 6.
Point out the functions of Election Commission.
Answer:
The Functions of Election Commission:

• Supervise the election.
• Prepare voters list.
• Declare the dates of different stages of election.
• Allot election symbols.
• Frame code of conduct.
• The appointment and training of election officials.
• Voting, counting of votes and declaration of results.
• Examine election expenses of candidates.

Kerala Syllabus 9th Standard Social Science Notes English Medium Question 7.
Name the first election commissioner of India.
Answer:
SukumarSen

9th Standard Social Science Notes Pdf In English Question 8.
Examine the drawbacks of India’s electroal system
Answer:
Drawbacks of India’s electroal system are given below
i) Influence of money

• Voters are influenced by offer of money.
• Political parties spend large amount of money for election campaigns.

ii) Election-related violence

• Violence on the polling day.
• Bogus voting and booth capturing.

(ii) influence of caste and religion
Caste and religious considerations influence selection of candidates.
(iv) Lack of representation of women

• Women do not get due consideration during the selection of candidates.
• Poor representation of women in the parliament and legislative assemblies

9th Standard Social Science Notes  Question 9.
Negative vote is casted by using button.
Answer:
NOTA

9th Standard Social Science Textbook Kerala Syllabus Question 10.
Define political parties. What are their functions?
Answer:
Political parties are organization formed on the basis of an ideology which works continuously for attaining political power. Their main functions are given below.

• Connect the government and the people.
• Form public opinion.
• Create political awareness.
• Context elections and the party attains majority of seats form the government.
• The parties which do not get majority of seats, function as responsible opposition.
• Correct wrong policies of government.
• Put forward various policies and programmes.

History 9th Class Kerala Syllabus Question 11.
Differentiate between national parties and state parties.
Answer:
National parties and state/regional parties are functioning in India. The Election Commission has set the criteria for political parties to be a national or state party.

Generally, those parties which function across the nation and have influence in more than one state are called national parties. Political parties which have influenced, only one state are called state parties.

9th Class Social Science Malayalam Medium Question 12.
What is meant by Psephology
Answer:
Psephology is the science of predicting election results before the declaration of results, after analyzing the possibilities of political parties and coalition fronts.

9th Class Social Science Notes Kerala Syllabus Question 13.
Who allots the symbols for the candidates who contest election?
Answer:
Election Commission

9th Class Social Science Malayalam Medium Notes Question 14.
What is the minimum age for contesting elections to different representative bodies?
Answer:
18 years

Scert Class 9 Social Science Notes Malayalam Medium Question 15.
Indian election system has drawbacks. Find ways to rectify them.
Answer:

• Identify card with voter’s photo.
• Limit on the election expenses of candidates.
• Code of conduct for political parties and candidates.
• Electronic voting machine.
• Voters’ list with photo of the electors.
• Negative voting system.
• Photo of candidates on ballot paper.

Question 16.
How is direct election different from indirect election? Find examples.
Answer:

• People directly elect their representatives. This method is called direct election.
  e.g: Loksabha, State legislative assembly, Local self-government.
• The method of election in which representatives are chosen by the elected representatives of people is indirect election.
  e.g: President, Vice President, Rajya Sabha

Question 17.
Elucidate what is proportional representation.
Answer:
In India, proportional representation is adopted where we follow indirect election. In India, MLAs of State Legislative Assemblies from each state elect members of the Rajyasabha. In proportion to their strength in the state legislative assemblies at each political party can elect representatives to Rajyasabha.

Students can Download Social Science Part 1 Chapter 3 Indian Constitution: Rights and Duties Questions and Answers, Summary, Notes Pdf, Activity in Malayalam Medium, Kerala Syllabus 9th Standard Social Science Solutions helps you to revise the complete Kerala State Syllabus and score more marks in your examinations.

Kerala State Syllabus Class 9th Standard Social Science History Chapter 3 Notes Malayalam Medium ഇന്ത്യൻ ഭരണഘടന: അവകാശങ്ങളും കടമകളും

Indian Constitution: Rights and Duties Textual Questions and Answers in Malayalam