CBSE Physics Class 12 Sample Paper 11 Page 1
Sample Paper 11
Class XII 2024-25
Physics
Time: 3 Hours Max. Marks: 70
General Instructions:
1. There are 33 questions in all. All questions are compulsory.
2. This question paper has five sections: Section A, Section B, Section C, Section D and Section E.
3. All the sections are compulsory.
4. Section A contains sixteen questions, twelve MCQ and four assertion reasoning based of 1 mark each,
Section B contains five questions of 2 marks each, Section C contains seven questions of 3 marks each,
Section D contains two case study based questions of 4 marks each and Section E contains three long
questions of 5 marks each.
5. There is no overall choice. However, an internal choice has been provided in one question in Section B,
one question in Section C, one question in each CBQ in Section D and all three questions in Section E.
You have to attempt only one of the choices in such questions
6. Use of calculators is not allowed.
7. You may use the following values of physical constants where ever necessary
i. c = 3 # 108 m/s
ii. me = 9.1 # 10−31 kg
iii. e = 1.6 # 10−19 C
iv. µ 0 = 4π # 10−7 TmA−1
v. h = 6.63 # 10−34 Js
vi. ε 0 = 8.854 # 10−12 C2 N−1 m−2
vii. Avogadro’s number = 6.023 # 1023 per gram mole
SECTION-A
1. The mutual inductance, when the magnetic flux changes by 5 # 10-2 Wb and current change by 0.01 A , is
(a) 0.2 H (b) 2.5 H
(c) 5 H (d) 10 H
2. Which of the following radiations have the least wavelength?
(a) X-rays (b) γ -rays
(c) β -rays (d) α -rays
3. A 10 µF capacitor is charged by a battery of e.m.f. 100 V. The electrostatic energy stored in the capacitor
is
(a) 0.5 J (b) 0.05 J
(c) 0.5 mJ (d) 0.05 mJ
4. If a diamagnetic substance is brought near north or south pole of a bar magnet, then it is
(a) attracted by the poles
(b) repelled by the poles
(c) attracted by the north pole and repelled by the south pole
(d) repelled by the north pole and attracted by the south pole
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Page 2 Sample Paper 11 CBSE Physics Class 12
5. Two insulated charged copper spheres A and B each having charge of 6.5 # 10-7 C are separated by a
distance 50 cm. If they are placed in water of dielectric constant 80, then electrostatic force of repulsion
between them is
(a) 1.9 # 10-7 N (b) 3.8 # 10-7 N
(c) 1.9 # 10-4 N (d) 3.8 # 10-4 N
6. A current-carrying coil is placed in a uniform magnetic field of induction B . The current in the coil is I
, it has n turns and A is the face area of coil and normal to the surface makes an angle θ with B . The
torque experienced by the coil is
(a) nIABθ (b) nIAB cos θ
(c) nIAB sin θ (d) nIAB tan θ
7. On connecting a battery to the two corners of a diagonal of a square conductor frame of side a , the
magnitude of magnetic field at the centre will be
µ
(a) zero (b) 0
πa
µ0 2µ 0
(c) (d)
2πa πa
8. As the electron in Bohr’s orbit of hydrogen atom passes from state n = 2 to n = 1, the kinetic energy K
and the potential energy u change as
(a) K four-fold and u two-fold
(b) K two-fold and u four-fold
(c) K two-fold and u also two-fold
(d) K four-fold and u also four-fold
9. An infinitely long conducting cylinder is kept parallel to a uniform magnetic field B directed along positive
z -axis. The direction of induced current on the surface of cylinder as seen from the z -axis will be
(a) zero (b) clockwise of the positive z -axis
(c) along the magnetic field (d) anticlockwise of the positive z -axis
10. The phenomenon of diffraction can be treated as the phenomenon of interference, if the number of
coherent sources are
(a) one (b) two
(c) zero (d) infinite
11. A steady current flows in a metallic conductor of non-uniform cross-section. Which of the following
quantity is constant along the conductor?
(a) current (b) drift speed
(c) current density (d) none of these
12. The kinetic energy of an electron, which is accelerated in the potential difference of 100 V is
(a) 1.6 # 10-17 J (b) 1.6 # 10-14 J
(c) 1.6 # 10-10 J (d) 1.6 # 10-8 J
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CBSE Physics Class 12 Sample Paper 11 Page 3
13. Assertion : The photoelectrons produced by a monochromatic light beam incident on a metal surface have
a spread in their kinetic energies.
Reason : The work function of the metal is its characteristics property.
(a) Both Assertion and Reason are correct and the Reason is a correct explanation of the Assertion.
(b) Both Assertion and Reason are correct but Reason is not a correct explanation of the Assertion.
(c) The Assertion is correct but Reason is incorrect.
(d) Both the Assertion and Reason are incorrect.
14. Assertion (A) : Charging is due to transfer of electrons.
Reason (R) : Mass of a body decreases slightly when it is negatively charged.
(a) Both Assertion and Reason are correct and the Reason is a correct explanation of the Assertion.
(b) Both Assertion and Reason are correct but Reason is not a correct explanation of the Assertion.
(c) The Assertion is correct but Reason is incorrect.
(d) Both the Assertion and Reason are incorrect.
15. Assertion : The number of electrons in a p -type silicon semiconductor is less than the number of electrons
in a pure silicon semiconductor at room temperature.
Reason : It is due to law of mass action.
(a) Both Assertion and Reason are correct and the Reason is a correct explanation of the Assertion.
(b) Both Assertion and Reason are correct but Reason is not a correct explanation of the Assertion.
(c) The Assertion is correct but Reason is incorrect.
(d) Both the Assertion and Reason are incorrect.
16. Assertion : Standard optical diffraction gratings can not be used for discriminating between X-ray
wavelength.
Reason : The grating spacing is not of the order of X-ray wavelengths.
(a) Both Assertion and Reason are correct and the Reason is a correct explanation of the Assertion.
(b) Both Assertion and Reason are correct but Reason is not a correct explanation of the Assertion.
(c) The Assertion is correct but Reason is incorrect.
(d) Both the Assertion and Reason are incorrect.
SECTION-B
17. The velocity of light in a liquid is 1.5 # 108 ms-1 and in air, it is 3 # 108 ms-1 . If a ray of light passes from
this liquid into air, calculate the value of critical angle.
18. Out of electric field vector Ev and magnetic field vector Bv in an electromagnetic wave, which is more
effective and why?
19. 1. How does a diamagnetic material behave when it is cooled to very low temperature?
2. Why does a paramagnetic sample display greater magnetisation when cooled? Explain.
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20. Name the important process that occurs during the formation of a p - n junction. Explain briefly, with
the help of a suitable diagram, how a p - n junction is formed. Define the term ‘barrier potential’.
O
Distinguish between an intrinsic semiconductor and a p -type semiconductor. Give reason why a p -type
semiconductor crystal is electrically neutral, although nh 22 ne .
21. He 23 and He 13 nuclei have the same mass number. Do they have the same binding energy?
SECTION-C
22. An electric dipole is placed in a uniform electric field E with its dipole moment p parallel to the field.
Find:
1. The work done in turning the dipole till its dipole moment points in the direction opposite to E .
2. The orientation of the dipole for which the torque acting on it becomes maximum.
23. Using de-Broglie’s hypothesis, explain with the help of a suitable diagram, Bohr’s second postulate of
quantization of energy levels in a hydrogen atom.
24. Show that a tangent galvanometer measures that current with maximum accuracy which produces 45c
deflection.
25. A wheel with 8 metallic spokes each 20 cm long is rotated with a speed of 120 rev/min in a plane normal
to the horizontal component of the Earth’s magnetic field. The Earth’s magnetic field at the plane is 0.4
G and the angle of dip is 60c. Calculate the emf induced between the axle and the rim of the wheel. How
will the value of emf be affected if the number of spokes were increased?
26. (i) When an AC source is connected to an ideal capacitor, then show that the average power supplied
by the source over a complete cycle is zero.
(ii) A lamp is connected in series with a capacitor. Predict your observations when the system is
connected first across a DC and then an AC source. What happens in each case if the capacitance
of the capacitor is reduced?
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27. Define the term “cut off frequency” in photoelectric emission. The threshold frequency of a metal is f .
When the light of frequency 2f is incident on the metal plate, the maximum velocity of photoelectrons is v1
. When the frequency of the incident radiation is increased to 5f , the maximum velocity of photoelectrons
is v2 . Find the ratio v1 : v2 .
O
Write Einstein’s photoelectric equation. State clearly the three salient features observed in photoelectric
effect which can explain on the basis of this equation.
The maximum kinetic energy of the photoelectrons gets doubled when the wavelength of light incident
on the surface changes from λ 1 to λ 2 . Derive the expressions to the threshold wavelength λ 0 and work
function for the metal surface.
28. In Young’s double slit experiment, the slits are 0.2 mm apart and the screen is 1.5 m away. It is observed
that the distance between the central bright fringe and fourth dark fringe is 1.8 cm . Find the wavelength
of light used.
SECTION-D
Case Study Based Questions.
Read the following paragraph and answer the questions that follow.
29. Light emitting diode is a photoelectric device which converts electrical energy into light energy. It is a
heavily doped p-n junction diode which under forward biased emits spontaneous radiation. The general
shape of the I-V characteristics of an LED is similar to that of a normal p-n junction diode, as shown. The
barrier potentials are much higher and slightly different for each colour.
(i) The I -V characteristic of an LED is
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(ii) The schematic symbol of light emitting diode is (LED)
(iii) An LED is constructed from a p-n junction based on a certain Ga-As-P semiconducting material
whose energy gap is 1.9 eV. Identify the colour of the emitted light.
(a) Blue (b) Red
(c) Violet (d) Green
(iv) Which one of the following statement is not correct in the case of light emitting diodes?
(a) It is a heavily doped p-n junction.
(b) It emits light only when it is forward biased.
(c) It emits light only when it is reverse biased.
(d) The energy of the light emitted is less than the energy gap of the semiconductor used.
O
The energy of radiation emitted by LED is
(a) greater than the band gap of the semiconductor used
(b) always less than the band gap of the semiconductor used
(c) always equal to the band gap of the semiconductor used
(d) equal to or less than the band gap of the semiconductor used.
30. Refraction of light is the change in the path of light as it passes obliquely from one transparent medium
to another medium. According to law of refraction sin i = 1 µ 2 , where 1 µ 2 is called refractive index of
sin r
second medium with respect to first medium. From refraction at a convex spherical surface, we have
µ2 µ1 µ2 − µ1
− = . Similarly from refraction at a concave spherical surface when object lies in the rarer
v u R
µ2 µ1 µ2 − µ1 µ µ µ − µ2
medium, we have − = and when object lies in the denser medium, we have 1 − 2 = 1
v u R v u R
(i) Refractive index of a medium depends upon
(a) nature of the medium (b) wavelength of the light used
(c) temperature (d) all of these
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(ii) A ray of light of frequency 5 # 1014 Hz is passed through a liquid. The wavelength of light measured
inside the liquid is found to be 450 # 10-9 m . The refractive index of the liquid is
(a) 1.33 (b) 2.52
(c) 2.22 (d) 0.75
(iii) A ray of light is incident at an angle of 60° on one face of a rectangular glass slab of refractive index
1.5. The angle of refraction is
(a) sin–1(0.95) (b) sin–1(0.58)
(c) sin–1(0.79) (d) sin–1(0.86)
(iv) A point object is placed at the centre of a glass sphere of radius 6 cm and refractive index 1.5. The
distance of the virtual image from the surface of sphere is
(a) 2 cm (b) 4 cm
(c) 6 cm (d) 12 cm
O
In refraction, light waves are bent on passing from one medium to the second medium because in
the second medium
(a) the frequency is different
(b) the co-efficient of elasticity is different
(c) the speed is different
(d) the amplitude is smaller
SECTION-E
31. Two cells of emfs e1 and e2 , and internal resistances r1 and r2 are connected in parallel between the points
A and B . Deduce the expressions for
1. the equivalent emf of the combination.
2. the equivalent resistance of the combination.
3. the potential difference between the points A and B .
O
Obtain an expression for the heat developed in a resistor by the passage of an electric current through it.
Hence state Joule’s law of heating.
32. (a) A capacitor of capacitance C is charged fully by connecting it to a battery of emf E . It is then
disconnected from the battery. If the separation between the plates of the capacitor is now doubled,
how will the following change ?
(i) charge stored by the capacitor.
(ii) field strength between the plates.
(iii) energy stored by the capacitor.
(b) Explain why, for any configuration, the equipotential surface through a point is normal to the
electric field at the point.
Draw a sketch of equipotential surfaces due to a single charge (- q), depicting the electric field lines due
to the charge.
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O
Show that the potential energy of a dipole making angle θ with the direction of the field is given by
u (θ) =− pv $ Ev . Hence, find out the amount of work done in rotating it form the position of unstable
equilibrium to the stable equilibrium.
33. What do you mean by wave front? Write down its type briefly?
O
Describe diffraction of light due to a single slit. Explain formation of a pattern of fringes obtained on the
screen and plot showing variation of intensity with angle θ in single slit diffraction.
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