# CBSE Class 12 Physics Sample Paper Set A

See below CBSE Class 12 Physics Sample Paper Set A with solutions. We have provided CBSE Sample Papers for Class 12 Physics as per the latest paper pattern issued by CBSE for the current academic year. All sample papers provided by our Class 12 Physics teachers are with answers. You can see the sample paper given below and use them for more practice for Class 12 Physics examination.

1. Two parallel large thin metal sheets have equal surface charge densities (s = 26.4 × 10–12 C m–2) of opposite signs. The  electric field between these sheets is
(a) 1.5 N C–1
(b) 1.5 × 10–10 N C–1
(c) 3 N C–1
(d) 3 × 10–10 N C–1

C

2. A gang capacitor is formed by inter locking a number of plates as shown in figure. The distance between the consecutive plates is 0.885 cm and the overlapping area of the plates is 5 cm2. The capacity of the unit is

(a) 1.06 pF
(b) 4 pF
(c) 6.36 pF
(d) 12.72 pF

B

3. The saturation current of a p-n junction diode made from germanium at 27°C is 10–5 A. What will be the required potential in order to obtain a current of 250 mA in forward bias?
(Boltzman constant k = 1.38 × 10–23 J K–1)
(a) 0.26 V
(b) 2.6 V
(c) 0.52 V
(d) 1.04 V

A

4. When a p-n junction diode made from germanium or silicion is forward-biased, energy is released at the junction due to the recombination of electrons and holes. This energy is in
(a) Visible region
(b) Infrared region
(c) UV region
(d) X-ray region

B

5. The Newton’s rings are seen in reflected light of wavelength 5896Å. The radius of curvature of plano-convex lens is 1.0 meter. An air film is replaced by a liquid whose refractive index is to be calculated under the conditions if 16th ring and its diameter is 5.1 mm.
(a) 1.45
(b) 2.90
(c) 1.73
(d) 2.50

A

6. Two flash light electric incandescent lamps, each requiring 3 A at 1.5 V are placed in series and connected to a 6 V cell. What resistance must be connected in series to operate them?
(a) 22 Ω
(b) 2 Ω
(c) 6 Ω
(d) 1 Ω

D

7. In the figure shown below the e.m.f. of the cell is 2 V and internal resistance is negligible.

The resistance of the voltmeter is 80 W. The reading of voltmeter will be
(a) 2.00 V
(b) 1.33 V
(c) 1.60 V
(d) 0.80 V

B

8. Four cells of identical emf E and internal resistance r are connected in series to a variable resistor. The following graph shows the variation of terminal voltage of the combination with current. The emf of each cell used is

(a) 1.4 V
(b) 5.6 V
(c) 2 V
(d) 1 V

A

9. In the given circuit, the voltmeter records 5 V. The resistance of the voltmeter in ohm is

(a) 200
(b) 100
(c) 10
(d) 50

B

10. ABCD is a rectangle whose side AB = 10 cm and side BC = 24 cm. A charge of 0.104 mC is lying at the center O of rectangle. If the mid-point of side BC is E, then the work done in carrying 100 mC charge from B to E will be
(a) 1.152 J
(b) 2.304 J
(c) 4.082 J
(d) 23.4 J

A

11. Name the gate represented by the following circuit

(a) OR gate
(b) XOR gate
(c) AND gate
(d) NAND gate

B

12. A 220 V input is supplied to a transformer. The output circuit draws a current of 2.0 A at 440 V. If the efficiency of the transformer is 80%, the current drawn by the primary windings of the transformer is
(a) 3.6 A
(b) 2.8 A
(c) 2.5 A
(d) 5.0 A

D

13. Three similar cells, each of emf 2 V and internal resistance r W send the same current through an external resistance of 2 W, when connected in series or in parallel. The strength of the current flowing through the external resistance is
(a) 1 A
(b) 1.5 A
(c) 2 A
(d) 0.75 A

D

14. In the Bohr’s model of hydrogen atom, the ratio of the kinetic energy to the total energy of the electron in nth quantum state is
(a) –1
(b) +1
(c) –2
(d) +2

A

15. Half-life of a radioactive substance is 20 minute. The time between 20% and 80%  decay will be
(a) 20 min
(b) 30 min
(c) 40 min
(d) 25 min

C

16. A transformer is used to light 140 W, 24 V lamp from 240 V ac mains. The current in the mains is 0.7 A. The efficiency of transformer is nearest to
(a) 90%
(b) 80%
(c) 70%
(d) 60%

B

17. The magnetic flux through a coreless solenoid carrying current I is 5 × 10–6 Wb. If the length of solenoid is 25 cm, its magnetic moment is equal to
(a) 1 A m2
(b) 10 A m2
(c) 12.5 A m2
(d) 125 A m2

A

18. A circular coil of radius 0.1 m has 80 turns of wire. If the magnetic field through the coil increases from 0 to 2 T in 0.4 s and the coil is connected to a 11 W resistor, what is the current through the resistor during the 0.4 s?
(a) (8/7) A
(b) (7/8) A
(c) 8 A
(d) 7 A

A

19. A power of transformer with an 8 : 1 turn ratio has 60 Hz, 120 V across the primary, the load in the secondary is 104 W. The current in the secondary is
(a) 96 A
(b) 0.96 A
(c) 9.6 A
(d) 96 mA

D

20. Each hadron consists of a proper combination of a few elementary components called
(a) photons
(b) vector bosons
(c) quarks
(d) meson-baryon pairs

C

21. A calcite crystal is placed over a dot on a piece of paper and rotated. On viewing through calcite, one will see
(a) a single dot
(b) two stationary dots
(c) two rotating dots
(d) one dot rotating about the other.

D

22. The hydrogen in a hydrogen bomb is converted into
(a) helium
(b) tritium
(c) plutonium
(d) uranium

A

23. Two copper balls, each weighing 10 g, are kept in air 10 cm apart. If one electron from every 106 atoms is transferred from one ball to the other, the coulomb force between them is (atomic weight of copper is 63.5)
(a) 2.0 × 1010 N
(b) 2.0 × 104 N
(c) 2.0 × 108 N
(d) 2.0 × 106 N

C

24. A torque of 10–5 N m is required to hold a magnet at 90° with the horizontal component of the earth’s magnetic field. The torque required to hold it at 30° will be
(a) 5 × 10–6 N m
(b) 1/2
(c) 5 √3 × 10–6 N m
(d) 2 × 10–6 N m

A

25. The potential difference in volt across the resistance R3 in the circuit shown in figure, is (Given, R1 = 15 Ω, R2 = 15 Ω, R3 = 30 Ω, R4 = 35 Ω)

(a) 5
(b) 7.5
(c) 15
(d) 12.5

C

26. An alpha particle of energy 5 MeV is scattered through 180° by a fixed uranium nucleus. The distance of closet approach is of the order of
(a) 10 Å
(b) 10–10 cm
(c) 10–12 cm
(d) 10–15 cm

C

27. An ac voltage source of variable angular frequency w and fixed amplitude V0 is connected in series with a capacitance C and an electric bulb of resistance R (inductance zero). When w is increased.
(a) the bulb glows dimmer
(b) the bulb glows brighter
(c) total impedance of the circuit is unchanged
(d) total impedance of the circuit increases.

B

28. An electron of mass m and charge q is travelling with a speed v along a circular path of radius r at right angles to a uniform magnetic field B. If speed of the electron is doubled and the magnetic field is halved, the resulting path would have a radius of
(a) r/4
(b) r/2
(c) 2r
(d) 4r

D

29. Gieger-Muller tube is a
(a) gas ionization detector
(b) cloud chamber
(c) Spectro Photometer
(d) fluorescent detector

A

30. The radiocarbon dating method is a realiable method for dating remains up to
(a) 50 years
(b) 500 years
(c) 5000 years
(d) 50000 years

D

31. Light of the wavelength 1500 Å fall on aluminium surface. Work function of aluminium is 4.2 eV. What is the kinetic energy of the fastest emitted photoelectrons?
(a) 2 eV
(b) 1 eV
(c) 4 eV
(d) 0.2 eV

C

32. If the series limit wavelength of Lyman series for the hydrogen atom is 912 Å, then the series limit wavelength for Balmer series of hydrogen atom is
(a) 912 Å
(b) 912 × 2 Å
(c) 912 × 4 Å
(d) 912/12 Å

C

33. One of the refracting surfaces of a prism of angle 30° is silvered. A ray of light incident at an angle of 60° retraces its path. The refractive index of the material of prism is
(a) √3
(b) 3/2
(c) 2
(d) √2

A

34. The focal length of objective and eye-piece of a microscope are 1 cm and 5 cm respectively.
If the magnifying power for relaxed eye is 45, then length of the tube is
(a) 9 cm
(b) 15 cm
(c) 12 cm
(d) 6 cm

B

35. Which one of the following is not correct about Lorentz Force?
(a) In presence of electric field E̅(r) and magnetic field B̅(r) the force on a moving electric charge is F̅ = q[E̅(r) + v̅ x B̅(r)] .
(b) The force, due to magnetic field on a negative charge is opposite to that on a positive charge.
(c) The force due to magnetic field become zero if velocity and magnetic field are parallel or anti-parallel.
(d) For a static charge the magnetic force is maximum.

D

36. A 4 A current carrying loop consists of three identical quarter circles of radius 5 cm lying in the positive quadrants of the x-y, y-z and z-x planes with their centres at the origin joined together, value of B̅ at the origin is

D

37. Two radioactive nuclei A and B have disintegration constants λA and λB and initially NA and NB number of nuclei of them are there. The time after which their undistintegrated nuclei are same is

C

38. The magnitude of angular momentum, orbit radius and frequency of revolution of electron in hydrogen atom corresponding to quantum number n are L, r, and u respectively. Then,
according to Bohr’s theory of hydrogen atom, which one is constant for all orbits.
(a) ur2L
(b) urL
(c) u2rL
(d) urL2

B

39. If angle of incidence is twice the angle of refraction in a medium of refractive index m, then angle of incidence is
(a) 2cos-1(μ/2)
(b) 2sin-1(μ/2)
(c) 2 cos–1(μ)
(d) 2 sin–1(μ)