P.S.E.B Sample Paper for 2024-25
Class: 12th
Subject: Physics
Time: 3 Hours
Max Marks: 70
Instructions:
- Question 1 contains 20 parts of 1 mark each.
- Questions 2 to 8 are of 2 marks each.
- Questions 9 to 15 are of 3 marks each.
- Question 16 (Comprehension) is of 5 marks.
- Questions 17 and 18 are of 5 marks each with internal choice.
- All questions are compulsory.
1. One mark questions:
(i) Electric field intensity due to an electric dipole of very small length at a point on the axial line at a distance r from its center varies as:
- (a) r
- (b) r²
- (c) r⁻³
- (d) r⁻⁴
(ii) The electric potential inside a conducting sphere is:
- (a) Zero
- (b) Increases from centre to the surface of the sphere.
- (c) Decreases from centre to the surface of the sphere.
- (d) Remains constant from centre to the surface of the sphere.
(iii) The electrical resistance of metals:
- (a) Increases with increase in temperature.
- (b) Is independent of temperature.
- (c) Decreases with increase in temperature.
- (d) None of the above.
(iv) The effect of temperature of the conductor on the drift velocity of electrons:
- (a) Varies linearly with temperature
- (b) Does not depend on the temperature
- (c) Increases with increasing temperature
- (d) Decreases with increasing temperature
(v) Path of a charged particle entering in uniform magnetic field at an angle 60° is:
- (a) Straight line
- (b) Helical
- (c) Parabola
- (d) Circular
(vi) Lenz’s law gives:
- (a) The magnitude of induced emf
- (b) Magnitude of induced current
- (c) The direction of induced emf
- (d) Both the magnitude and direction of induced emf
(vii) What is the angle between reflected ray and refracted ray when angle of incidence is equal to angle of polarization?
- (a) 90°
- (b) 0°
- (c) 30°
- (d) 120°
(viii) What will happen if the electron revolving around the nucleus of an atom becomes stationary?
- (a) Will move away from nucleus
- (b) Will fall into nucleus
- (c) Nothing will happen
- (d) None of the above
(ix) What is the name given to the type of electromagnetic waves used to capture photographs of Earth in foggy conditions:
- (a) Visible rays
- (b) UV rays
- (c) Microwaves
- (d) Infrared rays
(x) Which mirror is used as a shaving mirror?
- (a) Concave mirror
- (b) Convex mirror
- (c) Plane mirror
- (d) Parabolic mirror
(xi) The stopping potential depends upon:
- (a) Intensity of incident light
- (b) Energy of incident light
- (c) Surface area of the metal
- (d) Independent of Intensity of incident light
(xii) When Boron is added as impurity to silicon, the semiconductor becomes:
- (a) N-type semiconductor
- (b) P-type semiconductor
- (c) PN junction
- (d) None of the above
(xiii) Isolated magnetic poles called magnetic monopoles are not known to exist. This statement is the result of:
- (a) Gauss’s theorem in electrostatics
- (b) Gauss’s theorem in magnetism
- (c) Both a and b
- (d) None of the above
(xiv) Which of the following pairs is an isobar?
- (a) 1H and 2H
- (b) 2H and 3H
- (c) 14C and 14N
- (d) 40Ar and 40K
(xv) Wave front due to light source situated at infinity is:
- (a) Spherical
- (b) Cylindrical
- (c) Plane
- (d) None of the above
True/False:
(xvi) When forward biasing is applied to the PN junction, the width of the depletion layer increases. (True/False)
(xvii) Photoelectric effect is not possible for the light of all frequencies. (True/False)
(xviii) AC generator is based upon the principle of electromagnetic induction. (True/False)
(xix) Power of a thick lens is smaller than the thin lens. (True/False)
(xx) Sustained interference is caused by the superposition of two waves coming from two coherent sources. (True/False)
2. Two marks questions:
2. What do you mean by quantization of charge?
OR
What is the Coulomb’s force between two small charged spheres having charges of 2×10–9 C and 3×10–9 C separated by a distance of 30 cm?
3. Define Kirchhoff’s first and second law.
OR
A wire of length 15 m and uniform area of cross-section 6×10–7 m2 has a resistance of 5 Ω. Find the value of resistivity of the material of the wire.
4. Draw a labelled diagram of converting a galvanometer into an ammeter.
5. State Faraday’s law of electromagnetic induction.
6. Give any two uses of X-Rays.
7. Write Einstein’s photoelectric equation.
OR
Calculate de Broglie wavelength of an electron moving with speed of 6×106 m/s.
8. Write any two differences between nuclear fission and nuclear fusion.
3. Three marks questions:
9. What is an equipotential surface? Show that no work is done in moving a given charge over an equipotential surface.
10. With a circuit diagram, explain how a meter bridge can be used to determine the unknown resistance of a given wire.
11. Derive an expression for the force per unit length between two parallel current-carrying conductors. Explain the significance of the sign of the force.
12. State Huygens' principle. Using it, prove the laws of reflection of light.
13. Explain how an AC signal can be converted into a DC signal using a rectifier. Provide a circuit diagram and describe the working of the rectifier.
14. What is the resolving power of a microscope? Derive an expression for it.
15. What is the binding energy of a nucleus? Explain its significance. Calculate the binding energy per nucleon for 56Fe, given that the atomic mass of 56Fe is 55.93494 u.
4. Five marks question (Comprehension):
16. Read the passage given below and answer the following questions:
The earth behaves like a giant magnet with a magnetic field. The origin of the earth’s magnetic field is attributed to the dynamo effect, caused by the movement of molten iron and nickel in the outer core of the earth. The earth’s magnetic field resembles that of a magnetic dipole, with the magnetic field lines emerging near the geographic south pole and entering near the geographic north pole. The magnetic poles are not fixed and wander over time. Currently, the magnetic north pole is located at 86.50° N and 164.04° W, while the magnetic south pole is at 79.74° S and 108.22° E in Antarctica. Note that the magnetic north pole of the earth is a south pole and the magnetic south pole is a north pole according to the nomenclature of the bar magnet. The pole near the geographic north of the earth is called the north magnetic pole. Similarly, the pole near the geographic south is called the south magnetic pole. The intensity of the geomagnetic field is not the same at all points on the earth’s surface. The angle that the geomagnetic field makes with the horizontal direction at a point is called the dip angle. The lines along which the dip angle is zero are called the magnetic equator of the earth. Thus, the magnetic equator is roughly a circle passing through the center of the earth and lies between the geographic equator and the magnetic poles. The magnetic equator does not coincide with the geographic equator, but is inclined to it at an angle of approximately 11.3°. The dip angle is also called the inclination and is 90° at the magnetic poles.
Questions:
- (a) What is the typical strength of the Earth's magnetic field?
- (b) What is the Dynamo effect?
- (c) What is the approximate tilt between the Earth's magnetic dipole axis and its rotational axis?
- (d) Where is the Earth's magnetic north pole located?
- (e) What is the magnetic equator?
5. Five marks questions:
17. What is the principle of a transformer? Derive the expression for its efficiency.
OR
Explain the principle of working of a moving coil galvanometer and how it can be converted into a voltmeter.
18. Explain how an optical fiber works based on total internal reflection. Describe its applications in communication.
OR
Describe Bohr’s model of the hydrogen atom and derive the expression for the radius of the nth orbit.
