PRE-BOARD EXAMINATION 1 (2025-2026)
SUBJECT: PHYSICS (042)
CLASS: XII MARKS: 70 Marks
DATE: __/__/2025 DURATION: 180 Minutes
NAME: ________________________ ROLL NO: _________
GENERAL INSTRUCTIONS
o There are 33 questions in 6 pages. All questions are compulsory
o The question paper has five sections; Sections A, B, C, D and E.
o Section A contains twelve MCQs and four Assertion-Reason type questions of one mark each; Section
B contains five questions of two marks each; Section C contains seven questions of three marks each;
Section D consists of two Case-Based question of four marks; Section E contains three long answer
question of five marks each.
o For the questions under sections B, C and E, you must show your work to earn full marks.
o Calculators are not permitted and you may use the following table of natural constants.
TABLE OF NATURAL CONSTANTS
Speed of light in vacuum 𝑐 = 3.00 × 108 𝑚𝑠 −1
Fundamental unit of charge 𝑒 = 1.60 × 10−19 𝐶
Relative Permittivity ϵ0 = 8.85 × 10−12 𝐹. 𝑚−1
Relative Permeability μ0 = 4π × 10−7 𝑇𝑚. 𝐴−1
Avogadro’s Number 𝑁𝐴 = 6.023 × 1023 𝑚𝑜𝑙 −1
Mass of electron 𝑚𝑒 = 9.11 × 10−31 𝑘𝑔 = 0.0005485 𝑢
Mass of proton 𝑚𝑝 = 1.6726 × 10−27 𝑘𝑔 = 1.007276 𝑢
Mass of neutron 𝑚𝑛 = 1.6749 × 10−27 𝑘𝑔 = 1.0086649 𝑢
Atomic Mass Unit (AMU) 1𝑢 = 1.66054 × 10−27 𝑘𝑔
ℎ = 6.626 × 10−34 𝐽. 𝑠 = 4.135 × 10−15 𝑒𝑉. 𝑠
Planck’s Constant
ℎ𝑐 = 1239.8 × 10−9 𝑒𝑉. 𝑚 ≃ 1240 𝑒𝑉. 𝑛𝑚
SECTION A
Multiple Choice Questions
(1 × 16 = 16 Marks)
1) A conducting sphere of radius 20 𝑐𝑚 has an unknown charge. If the magnitude of the electric field at a
distance of 40 𝑐𝑚 from the center of the sphere is 1.2 × 103 𝑁𝐶 −1 and points radially inward, the net charge
on the sphere is: (1)
(A) −21 𝑛𝐶 (B) −5.3 𝑛𝐶 (C) +4.5 𝑛𝐶 (D) +5.3 𝑛𝐶
2) The electric field on the surface of a metal sphere of radius 20 𝑐𝑚 is 2.6 × 103 𝑁𝐶 −1 . The electric potential
difference between its surface and center is: (1)
(A) zero (B) 13 𝑉 (C) 52 𝑉 (D) 1.3 μ𝑉
3) If 1012 electrons move through a wire in five seconds, then the electric current through the wire is: (1)
(A) 16 𝑛𝐴 (B) 16 𝑝𝐴 (C) 32 𝑛𝐴 (D) 32 𝑝𝐴
4) Two long parallel wires that are 1.0 𝑚 apart carry currents 3.0 𝐴 and 1.0 𝐴 in opposite directions. The force
per unit length acting between them is: (1)
−7 −1 −7 −1
(A) 6.0 × 10 𝑁𝑚 ; Attractive (C) 6.0 × 10 𝑁𝑚 ; Repulsive
−5 −1
(B) 6.0 × 10 𝑁𝑚 ; Attractive (D) 6.0 × 10−5 𝑁𝑚−1; Repulsive
Page 1 of 6
, 5) In a coil of resistance 100 Ω , a current is induced by varying the magnetic flux through it for 0.5 𝑠. The
induced current decreases linearly with time from an initial value of 10 𝐴 to a final value of 0 𝐴, as shown in
Figure 1. The magnitude of the net change in magnetic flux during this interval is: (1)
(A) ΔΦ𝐵 = 20 𝑊𝑏
(B) ΔΦ𝐵 = 225 𝑊𝑏
(C) ΔΦ𝐵 = 250 𝑊𝑏
(D) ΔΦB = 500 Wb
Figure 1: Question 5
6) In a resonant AC circuit, the phase difference between total voltage and total current is: (1)
(A) 0𝑜 (B) 45𝑜 (C) 90𝑜 (D) 180𝑜
7) The type of EM waves involved in the greenhouse warming of earth’s surface is: (1)
(A) γ rays (B) microwaves (C) UV rays (D) Infra-red Rays
8) The bright, rainbow-like colors observed in a thin films such as soap bubbles or thin layer of oil floating on
water are produced due to: (1)
(A) Total Internal Reflection (TIR) (B) Dispersion (C) Diffraction (D) Interference
9) A postal stamp placed under a transparent rectangular slab of thickness 5.0 𝑐𝑚 and made of a material of
refractive index 𝑛𝑥 = 2.5. The stamp appears to have been shifted-up by: (1)
(A) 2.0 𝑐𝑚 (B) 3.0 𝑐𝑚 (C) 0.5 𝑐𝑚 (D) 2.5 𝑐𝑚
10) Wave front is defined as the locus of points in space which have the same: (1)
(A) Frequency (B) Amplitude (C) Intensity (D) Phase.
11) The ratio of the wavelengths of the Lymann-α (λ𝐿𝑦,α ) and Balmer-α (λ𝐵𝑎,α ) lines is: (1)
(A) λ𝐿𝑦,α : λ𝐵𝑎,α = 5: 27 (C) λ𝐿𝑦,α : λ𝐵𝑎,α = 1: 4
(B) λ𝐿𝑦,α : λ𝐵𝑎,α = 27: 5 (D) λ𝐿𝑦,α : λ𝐵𝑎,α = 4: 1
12) Which of the following atoms, when added to semiconductors, enhance the number density of holes in the
valence band? (1)
(A) Antimony (B) Boron (C) Carbon (D) Phosphorus
Questions 13 through 16 carry two statements – Assertion (A) and Reason (R). Answer these questions by
selecting the appropriate option from the ones given below.
(A) Both A and R are true, and R is the correct explanation of A.
(B) Both A and R are true, but R is not the correct explanation of A.
(C) A is true but R is false
(D) A is false but R is true.
13) Assertion (A): The net electric flux through a closed surface enclosing an electric dipole is null.
Reason (R): Electric monopoles do not exist. (1)
14) Assertion (A): A molecule is paramagnetic if it has unpaired electrons
Reason (R): Paramagnetism requires molecules with a net magnetic dipole moment. (1)
15) Assertion (A): Diffraction fringes are not of uniform width.
Reason (R): Diffraction is the spreading of wave into the region of geometrical shadow. (1)
16) Assertion (A): For a given frequency, higher photoelectric work function implies higher stopping potential.
Reason (R): Higher the kinetic energy of the ejected electrons, higher is the magnitude of the stopping
potential. (1)
Page 2 of 6
SUBJECT: PHYSICS (042)
CLASS: XII MARKS: 70 Marks
DATE: __/__/2025 DURATION: 180 Minutes
NAME: ________________________ ROLL NO: _________
GENERAL INSTRUCTIONS
o There are 33 questions in 6 pages. All questions are compulsory
o The question paper has five sections; Sections A, B, C, D and E.
o Section A contains twelve MCQs and four Assertion-Reason type questions of one mark each; Section
B contains five questions of two marks each; Section C contains seven questions of three marks each;
Section D consists of two Case-Based question of four marks; Section E contains three long answer
question of five marks each.
o For the questions under sections B, C and E, you must show your work to earn full marks.
o Calculators are not permitted and you may use the following table of natural constants.
TABLE OF NATURAL CONSTANTS
Speed of light in vacuum 𝑐 = 3.00 × 108 𝑚𝑠 −1
Fundamental unit of charge 𝑒 = 1.60 × 10−19 𝐶
Relative Permittivity ϵ0 = 8.85 × 10−12 𝐹. 𝑚−1
Relative Permeability μ0 = 4π × 10−7 𝑇𝑚. 𝐴−1
Avogadro’s Number 𝑁𝐴 = 6.023 × 1023 𝑚𝑜𝑙 −1
Mass of electron 𝑚𝑒 = 9.11 × 10−31 𝑘𝑔 = 0.0005485 𝑢
Mass of proton 𝑚𝑝 = 1.6726 × 10−27 𝑘𝑔 = 1.007276 𝑢
Mass of neutron 𝑚𝑛 = 1.6749 × 10−27 𝑘𝑔 = 1.0086649 𝑢
Atomic Mass Unit (AMU) 1𝑢 = 1.66054 × 10−27 𝑘𝑔
ℎ = 6.626 × 10−34 𝐽. 𝑠 = 4.135 × 10−15 𝑒𝑉. 𝑠
Planck’s Constant
ℎ𝑐 = 1239.8 × 10−9 𝑒𝑉. 𝑚 ≃ 1240 𝑒𝑉. 𝑛𝑚
SECTION A
Multiple Choice Questions
(1 × 16 = 16 Marks)
1) A conducting sphere of radius 20 𝑐𝑚 has an unknown charge. If the magnitude of the electric field at a
distance of 40 𝑐𝑚 from the center of the sphere is 1.2 × 103 𝑁𝐶 −1 and points radially inward, the net charge
on the sphere is: (1)
(A) −21 𝑛𝐶 (B) −5.3 𝑛𝐶 (C) +4.5 𝑛𝐶 (D) +5.3 𝑛𝐶
2) The electric field on the surface of a metal sphere of radius 20 𝑐𝑚 is 2.6 × 103 𝑁𝐶 −1 . The electric potential
difference between its surface and center is: (1)
(A) zero (B) 13 𝑉 (C) 52 𝑉 (D) 1.3 μ𝑉
3) If 1012 electrons move through a wire in five seconds, then the electric current through the wire is: (1)
(A) 16 𝑛𝐴 (B) 16 𝑝𝐴 (C) 32 𝑛𝐴 (D) 32 𝑝𝐴
4) Two long parallel wires that are 1.0 𝑚 apart carry currents 3.0 𝐴 and 1.0 𝐴 in opposite directions. The force
per unit length acting between them is: (1)
−7 −1 −7 −1
(A) 6.0 × 10 𝑁𝑚 ; Attractive (C) 6.0 × 10 𝑁𝑚 ; Repulsive
−5 −1
(B) 6.0 × 10 𝑁𝑚 ; Attractive (D) 6.0 × 10−5 𝑁𝑚−1; Repulsive
Page 1 of 6
, 5) In a coil of resistance 100 Ω , a current is induced by varying the magnetic flux through it for 0.5 𝑠. The
induced current decreases linearly with time from an initial value of 10 𝐴 to a final value of 0 𝐴, as shown in
Figure 1. The magnitude of the net change in magnetic flux during this interval is: (1)
(A) ΔΦ𝐵 = 20 𝑊𝑏
(B) ΔΦ𝐵 = 225 𝑊𝑏
(C) ΔΦ𝐵 = 250 𝑊𝑏
(D) ΔΦB = 500 Wb
Figure 1: Question 5
6) In a resonant AC circuit, the phase difference between total voltage and total current is: (1)
(A) 0𝑜 (B) 45𝑜 (C) 90𝑜 (D) 180𝑜
7) The type of EM waves involved in the greenhouse warming of earth’s surface is: (1)
(A) γ rays (B) microwaves (C) UV rays (D) Infra-red Rays
8) The bright, rainbow-like colors observed in a thin films such as soap bubbles or thin layer of oil floating on
water are produced due to: (1)
(A) Total Internal Reflection (TIR) (B) Dispersion (C) Diffraction (D) Interference
9) A postal stamp placed under a transparent rectangular slab of thickness 5.0 𝑐𝑚 and made of a material of
refractive index 𝑛𝑥 = 2.5. The stamp appears to have been shifted-up by: (1)
(A) 2.0 𝑐𝑚 (B) 3.0 𝑐𝑚 (C) 0.5 𝑐𝑚 (D) 2.5 𝑐𝑚
10) Wave front is defined as the locus of points in space which have the same: (1)
(A) Frequency (B) Amplitude (C) Intensity (D) Phase.
11) The ratio of the wavelengths of the Lymann-α (λ𝐿𝑦,α ) and Balmer-α (λ𝐵𝑎,α ) lines is: (1)
(A) λ𝐿𝑦,α : λ𝐵𝑎,α = 5: 27 (C) λ𝐿𝑦,α : λ𝐵𝑎,α = 1: 4
(B) λ𝐿𝑦,α : λ𝐵𝑎,α = 27: 5 (D) λ𝐿𝑦,α : λ𝐵𝑎,α = 4: 1
12) Which of the following atoms, when added to semiconductors, enhance the number density of holes in the
valence band? (1)
(A) Antimony (B) Boron (C) Carbon (D) Phosphorus
Questions 13 through 16 carry two statements – Assertion (A) and Reason (R). Answer these questions by
selecting the appropriate option from the ones given below.
(A) Both A and R are true, and R is the correct explanation of A.
(B) Both A and R are true, but R is not the correct explanation of A.
(C) A is true but R is false
(D) A is false but R is true.
13) Assertion (A): The net electric flux through a closed surface enclosing an electric dipole is null.
Reason (R): Electric monopoles do not exist. (1)
14) Assertion (A): A molecule is paramagnetic if it has unpaired electrons
Reason (R): Paramagnetism requires molecules with a net magnetic dipole moment. (1)
15) Assertion (A): Diffraction fringes are not of uniform width.
Reason (R): Diffraction is the spreading of wave into the region of geometrical shadow. (1)
16) Assertion (A): For a given frequency, higher photoelectric work function implies higher stopping potential.
Reason (R): Higher the kinetic energy of the ejected electrons, higher is the magnitude of the stopping
potential. (1)
Page 2 of 6
