Kerala Plus Two Physics Model Question Paper 4
Time: 2 Hours
Cool off time : 15 Minutes
General Instructions to candidates:
- There is a ‘cool off time’ of 15 minutes in addition to the writing time of 2 hrs.
- Your are not allowed to write your answers nor to discuss anything with others during the ‘cool off time’.
- Use the ‘cool off time’ to get familiar with the questions and to plan your answers.
- Read questions carefully before you answering.
- All questions are compulsory and only internal choice is allowed.
- When you select a question, all the sub-questions must be answered from the same question itself.
- Calculations, figures and graphs should be shown in the answer sheet itself.
- Malayalam version of the questions is also provided.
- Give equations wherever necessary.
- Electronic devices except non programmable calculators are not allowed in the Examination Hall.
Questions 1 and 2 carry 1 score each. Answer both.
Question 1.
Energy in a current carrying coil is stored in the form of
a. Electric field
b. magnetic field
c. dielectric strength
d. heat
Question 2.
Who indirectly determined the mass of the electron by measuring the charge of the electron ?
Answer any six questions from question number 3 to 10. Each question carries 2 scores.
Question 3.
Match the following
Question 4.
A student made a circuit as shown in the figure. S1 and S2 are switches and B is a bulb.
a. He argues that this circuit is equivalent to an AND gate. Do you agree with him? Justify your answer.
b. Write down its truth table.
Question 5.
Using the data given below, state as to which of the given lenses will you prefer to use as
i. an eye-piece and
ii. an objective to construct an astronomical telescope? Give reason for your answer.
Question 6.
Electromagnetic spectrum is an orderly arrangement of electromagnetic radiations in the j ascending or descending order of frequency/wavelength
a. Arrange the following electromagnetic radiations in the ascending order of frequency:
Visible rays, Infrared rays, X-rays, micro-waves.
b. Give one application of infrared and X-rays each.
Question 7.
A magnetic needle made of iron is suspended in a uniform external magnetic field. It experience a torque and the needle starts oscillating
a. Write down the frequency of oscillation of the magnetic needle.
b. If this magnetic needle is heated beyond curie temperature while it is oscillating, then its period.
i. increases
ii. decreases
iii. remains the same
iv. becomes infinity
Question 8.
a. An equilateral glass prism is placed on a horizontal surface. A ray PQ is incident I on it. For minimum deviation:
i. PQ is horizontal
ii. QR is horizontal
iii. RS is horizontal
iv. None of these
b. A thick lens gives coloured images due to
Question 9.
The truth table of a logic gate is given below.
a. Identify the gate.
b. Draw the logic symbol of the gate.
Question 10.
a. State Gauss’ law for magnetism.
b. How this differs from Gauss’ law for electrostatics ?
Answer any five question from question number 11 to 16. Each question carries 3 scores.
Question 11.
a. Which of the following symbol represents a universal gate ?
b. Shown below is an experimental set up with a semiconductor diode
i.identify the experiment
ii.draw the resulting graph.
c. With the help of neat circuit diagram obtain an expression for voltage gain of a transistor amplifier in C-E configuration.
Question 12.
a. The electrical analog of mass is
(i) diode
(ii) capacitance
(iii) inductance
(iv) resistance
b. A 2 m long solenoid having diameter 6 cm and 2000 turns has a secondary of 500 turns wound closely near its mid-point. Calculate the mutual inductance between the two coils.
Question 13.
What is de Broglie hypothesis ?
b. Write the formula for de Broglie wave length.
c. Calculate de Broglie wavelength associated with an electron accelerated by a potential difference of 100 volts. Given mass of the electron = 9.1×10-31kg, h= 6.634×10-34 JS,1 eV= 1.6×10-19J
Question 14.
Albert Einstein, the great physist proposed a clear picture to explain photoelectric effect.
a. Explain Einstein’s photo electric equation.
b. Name the quanta of light.
Question 15.
a. To construct an electronic circuit, you want to select a 470 KΩ resistor with 5% tolerance.Draw a schematic diagram indicating the colour combinations that you will select.
b. As the temperature of a metallic resistor is increased; the product of its resistivity and conductivity ………….
i. Increases
ii. Decreases
iii. Remains constant
iv. May increase or decrease
c. Draw a graph showing the relation between resistivity and temperature of a super conductor.
Question 16.
Earth behaves as a magnet with magnetic poles approximately near the geographic poles.
a. The order of magnitude of earth’s magnetic field in tesla is ….
b. What do you understand by ‘dynamo effect’?
c. Classify the following materials into diamagnetic and paramagnetic.
i. Lead
ii. Magnesium
iii. Tungsten
iv. Copper
Answer any four question from question number 17 to 21. Each question carries 4 scores.
Question 17.
When the magnetic flux associated with a coil changes an emf is induced in the circuit.
a. State Faraday’s law of electromagnetic induction.
b. Mention the physical significance of Lenz’s law with an example.
c. When an electrical appliance is switched off, sparking occurs. Why?
Question 18.
a. Obtain an expression for the number of radioactive nuclei present at any instant in terms of the decay constant and initial number of nuclei.
b. The half life of radioactive radon is 3.8 days. Find the time during which 1/20 of radon sample will remain undecayed.
Question 19.
Electric field lines are a pictorial representation of the electric field around charges.
a. State Gauss’s Law in Electrostatics.
b. Using this law derive an expression for the electric field intensity due to a uniformly charged thin spherical shell at a point.
i. Outside the shell
ii. Inside the shell
c. Suppose that you are in a cave deep within the earth. Are you safe from thunder and lightning ? Why ?
Question 20.
a. State Kirchhoff’s rules for the analysis of electrical circuits.
b. The circuit diagram of a potentiometer for the determination of internal resistance of a cell is shown below. Calculate the value of the internal resistance (r) of the cell.
Given R = 100 Ω, balancing length when key (K) open = 60 cm. Balancing length when key (K) closed = 58 cm.
Question 21.
We are familiar with the semiconductors Silicon and Germanium,
a. With a necessary schematic diagram, briefly explain the characteristics of an intrinsic semiconductor.
b. Draw the energy bands of a n-type semi-conductor.
c. The following figure represents a……..
Answer any three quest on from question number 22 to 25. Each question carries 5 scores.
Question 22.
Capacitor is an arrangement to increase the charge carrying capacity of a conductor
a. Each plate of a parallel plate capacitor has a charge q on it. The capacitor is now connected to a battery. Pick out the correct statement/statements.
i. The facing surfaces of the plates have equal and opposite charges.
ii. The battery supplies equal and opposite charges to the two plates.
iii. The two plates of the capacitor have equal and opposite charges.
b. The plates of a parallel plate capacitor each of area A is charged with charges +Q and -Q. Deduce the force acting between the plates of the capacitor.
c. Van de Graaff generator is a high voltage generator used to accelerate charged particles.
Draw a labelled schematic diagram of a Van De Graaff generator and state the principle behind its working.
Question 23.
Force acting on a charged particle when it moves in a combined electric and magnetic field is known as Lorentz force.
a. A charged particle is released from rest in a region of steady and uniform electric and magnetic fields; which are parallel to each other. What will be the nature of the path followed by the charged particle? Explain your answer.
b. A rectangular loop carrying a steady current is placed in a uniform magnetic field. Obtain the expression for the torque acting on the loop.
Question 24.
In the potentiometer circuit shown, the balance point is at X.
State with reason, where the balance point will be shifted, when
a. Resistance R is increased, keeping all parameters unchanged.
b. Resistance S is increased, keeping R constant.
c. Cell P is replaced by another cell whose e.m.f. is lower than that of cell Q.
d. You are asked to compare the emf of two cells using a potentiometer. Draw the circuit diagram for this and explain how you will determine the ratio of e.m.f.
Question 25.
In the figure PQ is a ray incident on a prism ABC.
a. Complete the ray diagram showing the passage of light. Mark angle of incidence i, angle of emergence e, angle of deviation δ and angle of refractions r1 and r2.
b. Using the diagram obtain the relation
δ = i + e – A.
c. The critical angle for diamond is 30°. What is its refractive index?
Answers
Answer 1.
b
Answer 2.
Thomson
Answer 3.
Answer 4.
a. No. It is an OR gate
b.
Answer 5.
i. For an eye piece we prefer convex lens of max power and min.aperture is lens L4.
ii. Objective must have minimum power and maximum aperture, ie., lens L1
Answer 6.
a. Microwaves, infrared, visible, x-rays
b. Infrared – Mobile phone (Bluetooth), TV, Video recorders.
X-ray – Detect the fracture of bones.
Answer 7.
b. increases
Answer 8.
a. QR is horizontal
b. disperson.
Answer 9.
a. NOR gate.
Answer 10.
a. Gauss’s law for magnetism states that the net magnetic flux through any closed surface is zero, i.e.,
b. Gauss’s law in electrostatics states that the total flux through a closed surface is 1/ε0 times the net charge enclosed by the closed surface.
Answer 11.
a. (ii)
b. (i) For studying the V-I characteristics of a p-n junction diode.
Answer 12.
a. (iii) inductance
Answer 13.
a. He proposed that material particles in motion should display wave-like properties.
Answer 14.
a. Einstein explained photoelectric effect based on quantum theory. According to quantum theory, light contain photons having energy hυ, when a photon of energy hυ0 incident on a metal surface, electrons are liberated. A small portion of the photon energy is used for work function (φ) and remaining energy is appeared as K.E of the electrons.
By law of conservation of energy, we can write hυ = hυ0 + ½ mv²; hυ energy of incident wave ; hυ0 -» work function ½mv² -» K.E of electron
b. Photon.
Answer 15.
Answer 16.
a. 10-5 T or 0.38 x 10-4 T
b. Earth magnetic field arises due to electrical currents produced by convective motion of metallic fluids in the outer core of the earth. This is called dynamo effect.
c. Lead, Copper – Dia magnetic
Magnesium, Tungsten – Para magnetic
Answer 17.
a. Faraday’s first law: According to first law an EMF is induced in a circuit.when the magnetic flux linked with it changes.
b. Lenz’s law verifies conservation of energy in the electromagnetic induction phenomenon.
When N-pole of a bar magnet is moved towards a coil, the direction of induced current in the coil will be such that the end 2 will behave as N-pole (to oppose the incoming N-pole). For this the current in the coil will be anticlockwise as seen from the right face of the coil (using right hand thumb rule).
c. Due to back emf.
Answer 18.
t = 3.8 x 4.33 = 16.45 days
Answer 19.
a. Gauss’s Law states that the total flux through a closed surface is 1/ε0 times the net charge enclosed by the closed surface.
b. (i).Outside the sphere (r > R)
c. Yes. This is because the electric field inside the cave will be zero. This is called electrostatic shielding.
Answer 20.
a. First law: The total current entering the junction is equal to the total current leaving the junction.
Second law: Total emf in a closed circuit is equal to the sum of the voltage drops.
Answer 21.
A pure semiconductor which is free from any impurity is called intrinsic semiconductor. Its conductivity controlled by the number of valence electron present in valence band. At 0K no electron is available in the conduction band semiconductor act as insulator.
c. Diode.
Answer 22.
a. i. True ii. True iii. True
c. The high electric field at the pointed ends of comb C1, ionises the air near them. The +ve charges in air are repelled and got deposited on the belt through a corona discharge.
The charges are carried upto C2. A similar corona discharge takes place at C2 and the charges are finally transferred to the shell M. The charges spread over uniformly on the outer surface of M raising its potential to few million volts.
Answer 23.
a. The charged particle execute an accelerated straight line motion along the direction of electric field. Since the electric field and magnetic field are parallel the magnetic field will be in the direction of the motion of the charged particle and hence the force due to magnetic field will be zero.,
b. A rectangular loop carrying a steady current I and placed in a uniform magnetic field experiences a torque. It does not experience a net force.
Consider a rectangular coil ABCD, placed in a uniform magnetic field, B. Then,
τ = I ab B = NIAB sin θ or τ =M x B ,
where A is the area of the coil, N is the no of turns. Here M = I (NA) is called magnetic dipole moment. If θ = 0 or 180, τ = 0.
Answer 24.
a. Balance point will be shifted towards B.
b. No change.
c. Balance point not found on AB.
Potential difference between two points of a current carrying conductor is directly proportional to the length of the wire between the two points.
A battery (B1), Rheostat and key are connected in between A and B. This circuit is called primary circuit. Positive end of E1 and E2, are connected to A and other ends are connected to a two way key. Jockey is connected to a two key through galvanometer. This circuit is called secondary circuit.
Key in primary circuit is closed and then E1 is put into the circuit and balancing length I1 is found out.
Answer 25.
