Class 12 Pre-Board Sample Paper 2025 Physics

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Pre-Board Exam 2025 Sample Question Paper

SUBJECT- PHYSICS(THEORY)
CLASS-XII

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 two marks each, Section C
contains seven questions of three marks each, Section D contains two case study
based questions of four marks each and Section E contains three long answer
questions of five 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 x 108 m/s ii. me = 9.1 x10-31 kg iii. e =
1.6 x 10-19 C iv. µ0 = 4π x 10-7 Tm𝐴 −1 v. h = 6.63 x10-34 Js vi. ε0 = 8.854 x10-12 𝐶 2𝑁
−1𝑚−2 vii. Avogadro’s number = 6.023 X 1023 per gram mole

SECTION A
Q1 Torque acting along on electric dipole of dipole moment P placed in 1
uniform electric field E is:
(a) P x E (b) P E (c) P x(E x P ) (d) E x P
Q2 .The electrostatic force between the metal plates of an isolated
parallel plate capacitor C having a charge Q and area A, is
(a) proportional to the square root of the distance between the
1
plates. (b) linearly proportional to the distance between the plates.
(c) independent of the distance between the plates.
(d) inversely proportional to the distance between the plates
Q3. In a Whetstone’s bridge, all the four arms have equal resistance R. If 1
resistance of the galvanometer arm is also R, then equivalent
resistance of the combination is-
(A) R
(B)2R
(C)R/2
(D)R/4
Q4 The force experienced by a charged particle moving in a magnetic 1
field is maximum when the angle between the velocity of the
particle and the magnetic field is:
a) 0°
b) 45°
c) 90°
d) 180°
Q5 The magnetic susceptibility of a diamagnetic substance is 1
(a) ∞
(b) zero
(c) small but negative
(d) small but positive

Q6 Lenz’s law of electromagnetic induction is as per law of 1
conservation of
a) energy.

b) angular momentum.
c) charge.
d) electromotive force.
Q7 When current in a coil changes from 5 A to 2 A in 0.1 s, average
voltage of 50V is produced. The self-inductance of the coil is V is
1
produced. The self-inductance of the coil will be.
(a) 1.67 H
(b) 6 H
(c) 3 H
(d) 0.67 H
Q8 An ac circuit has a resistance of 12 ohms and an impedance of 15 1
ohms. The power factor of the circuit will be
(a) 0.8
(b) 0.4
(c) 0.125
(d) 1.25
Q9 What happens to the inductive reactance when the frequency of the 1
AC supply is increased?
(a) Increases
(b) Decreases
(c)Remains the same
(d) Decreases inversely
Q10 The electromagnetic radiation used for water purification and eye
surgery is
(a)infrared
1
(b)microwave
(c) X-rays
(d) ultraviolet wave
Q11 The emission of electron from a surface is possible due to 1

(a) Photoelectric effect
(b) Thermionic effect
(c) Both (a) and (b)

(d) None of the above
Q12 For a nuclear fusion process, suitable nuclei are 1
(a.) Any nuclei
(b)Heavy nuclei
(c) Light nuclei
(d).Nuclei lying in middle of periodic table
ASSERTION –REASON QUESTION DIRECTIONS: Read the
following questions and choose any one of the following four
responses. EACH QUESTION OF 1 MARK
A. If both assertion and reason are true and reason is the
correct explanation of the assertion.
B. if both assertion and reason are true but reason is not a
correct explanation of assertion.
C. If assertion is true but reason is false.
D. If both assertion and reason is false.
Q13 Assertion: Diffraction takes place for all types of waves mechanical 1
or non-mechanical, transverse or longitudinal.
Reason :Diffraction’s effect are perceptible only if wavelength of
wave is comparable to dimensions of diffracting device.
Q14 . Assertion (A): A very intense beam of light having frequency less 1
than the threshold frequency does not cause photoelectric emission
Reason (R) : Photoelectric emission is only possible if the frequency
of incident radiation is greater than the threshold frequency.
Q15 Assertion: The depletion layer in p-n junction under forward bias 1
decreases.
Reason: The electric field due to external voltage supports the
electric field due to potential barrier..
Q16 Assertion: Density of nuclear matter is same for all nuclei. 1
Reason: Density has nothing to do with mass and size of the
nucleus
SECTION B
Q17 Two point charges of 3 x10 -8C and -2 x10 -8 Care placed 15 cm

apart in air. At what point on the line joining the two charge is the
2
electric potential zero? Take the potential at infinity to be zero
Q18 Name the part of electromagnetic spectrum whose wavelength lies 2

in the range 10-10m. Give its one use.
Q19 Under what conditions does the phenomenon of total internal 2
reflection take place? Draw a ray diagram showing how a ray of
light deviates by 90° after passing through a right-angled isosceles
prism.
Q20 Assume that the frequency of the radiation incident on a metal plate 2
is greater than its threshold frequency. How will the following
change, if the frequency of incident radiation is doubled?
(1) Kinetic energy of electrons (2) Photoelectric current
Or
A proton and an electron have same kinetic energy. Which one has
greater de- Broglie wavelength.
Q21 Define the terms (i ) depletion region and (ii) potential barrier. 2

SECTION C
Q22 State Gauss’s law in electrostatics. Using this law derive an 3
expression for the electric field due to a uniformly charged infinite
plane sheet.
Q23 State Kirchhoff’s laws. In the electric network shown in the figure, 3
use Kirchhoff’s rules to calculate the power consumed by the
resistance R=4Ω

Q24 3. A solenoid has a core of a material with relative permeability 400. 3
The winding of solenoid is insulated from the core and carry a
current of 2A. If the number of turn is 1000 per metre, calculate 1.H
2. M and 3. B
Q25 In a series L-C-R circuit, obtain the conditions under which (i) the 3
impedance of circuit is minimum and (ii) wattles current flows in
the circuit.
OR
4. An AC source of voltage V = Vm sin wt is applied across a series

L-C-R Draw the phasor diagram for this circuit when the
(a)capacitive impedance exceeds the inductive impedance. (b)
inductive impedance exceeds the capacitive impedance.

Q26 Draw a ray diagram for the formation of image of a point object by a 3
thin double convex lens having radii of curvature R1 and R2. Hence
derive lens maker’s formula.
Q27 The work function of Caesium metal is 2.14eV. When light of 3
frequency 6 x 1014 Hz is incident on the metal surface
photoemission of electrons occurs. (a). What is the maximum
kinetic energy of the emitted (b). stopping potential and maximum
speed of the emitted photoelectrons
Q28 1. Draw the plot of binding energy per nucleon curve as a function 3
of mass number.
2. write two characteristics of nuclear forces.

SECTION D
Q29 CASE BASED QUESTION -

Young’s double-slit experiment uses two coherent sources of light
placed at a small distance apart, usually, only a few orders of
magnitude greater than the wavelength of light is used. Young’s
double-slit experiment helped in understanding the wave theory of
light which is explained with the help of a diagram. A screen or
photo detector is placed at a large distance ’D’ away from the slits as
shown. The original Young’s double-slit experiment used diffracted
light from a single source passed into two more slits to be used as
coherent sources. Lasers are commonly used as coherent source in
the modern-day experiments.
i. In Young’s Double Slit Experiment, if instead of monochromatic
light white light is used, what would be the observation?
(a) The pattern will not be visible
(b) The shape of the pattern will change from hyperbolic to circular
(c) Coloured fringes will be observed with a white bright fringe at
the centre (d) The bright and dark fringes will change position
ii. What kind of sources is required for Young’s Double Slit
experiment?
(a) Coherent
(b) Incoherent

(c) Intense
(d) Bright

iii. If the distance between the two slits is doubled, the fringe width
_________
(a) Doubles
(b) Halves
(c) Four-times
(d) Remains same
iv. There is no effect on the interference pattern when the width of
the slit is increased.
(a) True (b) False
OR
What is the effect on angular width of the fringes if screen distance
increases
a) Doubles
(b) Remains same
(c) Four-times
(d) Halves

Q30 From Bohr's atomic model, we know that the electrons have well
defined energy levels in an isolated atom. But due to inter atomic
interactions in a crystal, the electrons of the outer shells are forced
to have energies different from those in isolated atoms. Each energy
level splits into a number of energy levels forming a continuous
band. The gap between top of valence band and bottom of the
conduction band in which no allowed energy levels for electrons can

exist is called energy gap.
(i) In an insulator energy band gap is

(a) Eg= 0
(b) Eg< 3eV
(c) Eg> 3eV
(d) None of the above

(ii) In a semiconductor, separation between conduction and valence
band is of the order of
(a) 0 eV
(b) 1eV
(c) 10 eV
(d) 50 eV
(iii) Based on the band theory of conductors, insulators and
semiconductors, the forbidden gap is smallest in
(a) conductor (b) insulator (c) semiconductors (d) All of these.
(IV)In semiconductors at a room temperature
(a) the valance band is partially empty and the conduction band is
partially filled.
(b) the valance band is completely filled and the conduction band is
partially filled.
(c) the valance band is completely filled.
(d) the conduction band is completely empty.
OR
If no external voltage is applied across p-n junction, then there
would be
(a) no electric field across the junction
(b) an electric field pointing from n-type to p-type side across the
junction
(c) an electric field pointing from p-type to n-type side across the
junction
(d) a temporary electric field during formation of p-n junction that
would subsequently disappear

SECTION E
Q31 Using the concept of free electrons in a conductor, derive the 5
expression for the resistivity of a wire in terms of number density
and relaxation time. Hence obtain the relation between current
density and the applied electric field E.
Or
(a) (i) Why do the ‘free electrons’, in a metal wire, ‘flowing by
themselves’, not cause any Current flowing in the wire? (ii)Explain
the term ‘drift velocity’ of electrons in a conductor. Derive the
expression of drift velocity Hence obtain the expression for the
current through a conductor in terms of ‘drift velocity’
(b) Use the above expression to show that the ‘resistivity’, of the
material of a wire, is proportional to the Relaxation time
Q32 (a) Using Biot-Savart’s law, derive an expression for the magnetic
field at the centre of a circular coil of radius R, number of turns N,
carrying current I.
(b) Two small identical circular coils marked 1, 2 carry equal
currents and are placed with their geometric axes perpendicular to
each other as shown in the figure. Derive an expression for the
resultant magnetic field at O.

Or
(a)Two straight long parallel conductors carry currents I1 and I2 in
the same direction. Deduce the expression for the force per unit

length between them. Depict the pattern of magnetic field lines
around them. (b) A rectangular current carrying loop EFGH is kept
in a uniform magnetic field as shown in the figure. (i) What is the
direction of the magnetic moment of the current loop? (ii) When is
the torque acting on the loop (A) maximum, (B) zero?

Q33 Draw a schematic labelled ray diagram of a reflecting type
telescope. (ii) Writing two important advantages justifying why
reflecting type telescopes are preferred over refracting telescopes.
(iii) The objective of a telescope is of larger focal length and of
larger aperture. Why? give reasons
Or
Draw a labelled ray diagram of a refracting telescope. Define its
magnifying power and write the expression for it. Write two
important limitations of a refracting telescope over a reflecting type
telescope.

CLASS XII
SUBJECT-PHYSICS
PRE BOARD MARKING SCHEME

S.NO ANS
1 a 1
2 c 1
3. a 1
4 c 1
5 c 1
6 a 1
7 a 1
8 a 1
9 a 1
10 d 1
11 c 1
12 c 1
13 b 1
14 a 1
15 c 1
16 a 1
17 Given, q1 = 3 x10 -8C, q2 = -2 x10 -8C, r = 15 2
cm, x=? Let O be the point, where the electric
potential is zero due to the two charges (fig.)
Suppose that the distance AO = x and OB =
15-x 24 Electric potential at point O due q1 V1
= 𝑞1 4𝜋ɛ0 𝑥 = 9 x 109X 3 X 10−8 𝑥 = 270 𝑥
Electric potential at point O due q2 V2 = 𝑞1
4𝜋ɛ0 (15−𝑥) = 9 x 109X 2 x 10−8 𝑥 = 280 15−𝑥
Since the electric potential at point O is zero,
we have V1 + V2 = 0, 280 15−𝑥 = 270 𝑥 x =
9cm from q
18 The electromagnetic waves having wavelength 2
10-10m are x-rays.
X-rays are used to study crystal structure
19 1. Light travels from denser to rarer 1
medium. 2. Angle of incidence in
denser medium must be greater than
the critical angle.
2. Correct ray diagram 1
20 If the frequency of the incident 1
radiation is doubled is increased,
hence kinetic energy is increased. (2)
If the frequency of the incident
radiation is doubled there will be no
change in the number of 1
photoectrons i.e. photoelectronic
current.
Or
Correct answer 2

21 Definition of depletion region 1
Definition of potential barrier 1

SECTION C

Q22 Statement 1
derivation 2

Q23 KVL ½
KCL ½
For two correct equations ½+½
For correct answer 1
Q24 1. H =nI = 2×10³ A/m 2. B = μH =1.0T 1
3. M = XH =8×10 J A/m 1
1
25 Z=R OR RESONSNCE 1+1/2
XL>XC OR XL<XC 1+1/2
OR
CORRECT PHASOR DIAGRAM 3
26 DIAGRAM 1
DERIVATION 2

27 : 1. Kmax = hv – ϕ0 = (6.63x10-34 1
x 6 x1014
/ 1.6x10-19 ) – 2.14eV = 0.314 eV
ii) eVo = Kmax = 0.314eV V0 = 0.314V 1
iii) Vmax = 345.8 X 103
m/s 1
28 B.E/A VS A CURVE 2
TWO CHARACTERISTICS 1

SECTION D

29 Case study
(i) c (ii) a (iii) b (iv) b OR b 4

4
30 (I)(c) (ii) (b) (iii) (a)
(IV) (a) OR (b)

SECTION E

31 Derivation 3
Relation between current density and 2

E
OR
(a)i reason ½
Ii explanation ½
Derivation 1+1

(b) derivation 2
32 (a) Derivation of magnetic field at 2
centre of the coil
(b) Derivation of resultant magnetic
field 1
(a) Or(i)the expression for the
force per unit length 1
(ii)pattern of magnetic field
lines around them
Magnetic moment will be ½+1/2
out of the plane from the
surface HEFG. (ii) Torque
(A) Torque is maximum
when MII B i.e., when it
gets rotated by 90°. (B)
Torque is minimum when
M and B are at 270° to each
other

33 Diagram 2
(i) Two advantages 2
(ii) Reason
1
Or 2
Diagram 1
definition
Two limitations 2

½+1/2

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