Class 12 Half Yearly Question Paper 2025-26 Physics

CBSE CLASS 12
Half Yearly Question Paper
Session 2025-26

PHYSICS

Exam CBSE Class 12
Subject Physics
Session 2025-26
Document Type Half Yearly Question Paper

Notes · Sample Papers · Previous Year Papers · Mock Tests

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Question Paper
HALF YEARLY EXAMINATION�
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SESSION – 2025-2026�
CLASS: XII� � � � � � MAXIMUM MARKS: 70�
SUBJECT: Physics� � � � � � � TIME: 3 Hours�
__________________________________________________________________________�
General Instructions:�
Read the following instructions very carefully and strictly follow them:�

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(i) This question paper contains 33 questions. All questions are compulsory.�
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(ii) This question paper is divided into five sections – A, B, C, D and E.�

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(iii) In Section A – Questions no. 1 to 16 are Multiple Choice (MCQ) type questions, carrying 1 mark each.�

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(iv) In Section B - Questions no. 17 to 21 are Very Short Answer (VSA) type questions, carrying 2 marks each.�
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(v) In Section C - Questions no. 22 to 28 are Short Answer (SA) type questions, carrying 3 marks each.�
(vi) In Section D - Questions no. 29 and 30 are case study based questions, carrying 4 marks each.�
(vii) In Section E - Questions no. 31 to 33 are Long Answer (LA) type questions, carrying 5 marks each.�
(viii) There is no overall choice given in the question paper. However, an internal choice has been provided
in few questions in all the sections except Section A.�
You may use the following values of physical constants wherever necessary:�
c = 3 x 108 m/s�
h = 6.63 x 10-34 Js�

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e = 1.6 x 10-19 C�

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μ0 = 4π x 10-7 Tm/A�
ϵ0 = 8.85 x 10 -12 C2N-1m-2�
e m
1
= 9 x 109 Nm2C-2�
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4𝜋𝜖0
Mass of electron (me) = 9.1 x 10-31 kg�
Mass of neutron = 1.675 x 10-27 kg�
Mass of proton = 1.673 x 10-27 kg�
Avogadro number = 6.023 x 1023�
Boltzmann constant = 1.38 x 10-23 JK-1�
SECTION-A�
1� Four charges + 8Q, - 3Q +5Q and -10Q are kept inside a closed surface. What will be the 1�

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outgoing flux through the surface? �

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(a) 26 Vm � (b) 0 Vm � (c) 10 Vm � (d) 8 Vm�

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2� Which of the following graphs shows the variation of electric field E due to a hollow 1�

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spherical conductor of radius R as a function of distance from the centre of the sphere? �
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3� In a parallel plate capacitor, the capacitance increases if� 1�

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(a) Area of the plate is decreased. (b)Distance between the plates increases.�

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(c) Area of the plate is increased. (d) Dielectric constant decreases.�
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4� Two capacitors 3 µF and 6 µF are connected in series and connected to 100 V d.c. source. 1�
What is the ratio of energies stored in them �
(a) 1:2 ( b) 1:3 (c) 2:1 (d) 3:1�
5� Figure represents a part of closed circuit. The potential difference between points A and B (VA- 1�
VB) is �

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(a) +9 V � (b) -9 V � (c) +3 V � (d) +6 V �
6� If a wire is stretched to “n” times of its original length, it’s new resistance will be – � 1�
(a) R/n � (b) nR (c) 𝑛2 R � (d) n/R �
7� The deviation through the prism is maximum when angle of incidence is� 1�
(a) 450 (b) 300 (c) 900 (d)600 �
8� If the critical angle for total internal reflection from a medium to vacuum is 45°, then velocity 1�
of light in the medium is �
(a) 3.12 x108 m/s � (b) 2.12 x108 m/s � (c) 1.5 x108 m/s � (d) 1.12 x108 m/s �
9� A given convex lens of glass (n= 3/2) can behave as concave if it is held in a medium of 1�
refractive index n equals to �
(a)1 (b) 3/2 (c) 2/3 (d) 7/4�
10� In Bohr model of hydrogen atom, which of the following is quantized? � 1�
(a) Linear velocity of electron (b) Angular velocity of electron �
(c) Linear momentum of electron � (d) Angular momentum of electron. �
11� The graph which depicts the results of Rutherford gold foil experiment with α particles (where 1�
θ= scattering angle, Y= no. of scattered α particles detected) �
�

12� R1 and R2 are the radii of atomic nuclei of mass numbers 64 and 27 respectively. The ratio of 1�
R1 and R2 is �
(a) 64 / 27 (b) 27 / 64 (c) 4 / 3 (d) 1�
Questions number 13 to 16 are Assertion(A) and Reason(R) type questions. Two statements are given –
one labelled Assertion(A) and the other labelled Reason(R). Select the correct answer from the codes (A),
(B), (C) and (D) as given below.�
A.� Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the
Assertion (A).�
B.� Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the
Assertion (A).�
C.� Assertion (A) is true, but Reason (R) is false. �
D.� Assertion (A) is false and Reason (R) is true.�

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. c 13� Assertion (A): On disturbing an electric dipole in stable equilibriumseinman electric field, it
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returns back to its stable equilibrium orientation.�
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Reason(R): A restoring torque acts on the dipole on being disturbed
equilibrium.�
14� Assertion (A):- If a dielectric is placed in external field, then field inside dielectric will be 1�
less than applied field.�
Reason (R):- Electric field will induce dipole moment opposite to field direction.�
15� Assertion (A): When Wheatstone bridge is balanced then current through cell depends on 1�
resistance of galvanometer. �

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Reason (R): At balanced condition current through galvanometer is zero. �

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16� Assertion(A): Total energy of an electron in a hydrogen atom is negative.� 1�

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Reason (R): Electron is bounded to the nucleus.�

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SECTION-B�
17�
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Use Gauss’s law to obtain the expression for the electric field due to a uniformly charged
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infinite plane thin sheet.�
18� The figure shows a network of five capacitors connected to a 100 V supply. Calculate the total
charge in the network.�
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laequal to C = C, C = 2C, C = 3C and C = 4C are
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OR�

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A network of four capacitors of capacitance 1 2
connected to a battery as shown in figure. Find the ratio of charges on C and C .�
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2 4
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c. (a)o𝐻 Calculate m
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19� the energy in fusion reaction:� 2�

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+ 𝐻 2
→ 𝐻𝑒3
+ 𝑛 , where BE of 𝐻 = 2
2.23 MeV and of 𝐻𝑒 =
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MeV� 3

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Or�
From the relation 𝑅 = 𝑅0 𝐴 , where R0 is constant and A is the mass number of nucleus, show
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that nuclear matter density is independent of A.�
20� A conductor of length ‘l’ is connected to a DC source of potential difference V. If length of 2�
the conductor is tripled by gradually stretching it, by keeping V constant, how will �
(i)� Drift speed of electrons and �
(ii) Resistance of the conductor is affected? Justify your answer.�

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21� Find the change in power dissipated in the 4 Ω resistor after the switch S is closed. � 2�
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SECTION-C�
22� A charge Q is distributed over the surfaces of two concentric hollow spheres of radii r and R 3�
(R >> r), such that their surface charge densities are equal. Derive the expression for the
potential at the common centre.�
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23� Figure shows two identical capacitors C1 and C2 each of 2 µF capacitance, connected to a
battery of 5 V. Initially switch ‘S’ is closed. After some time switch ‘S’ is left open and
dielectric slabs of dielectric constant K = 5 are inserted to fill
completely the space between the plates of the two capacitors.
How will the�
(i)�Charge and�
(ii) Potential difference between the plates of the capacitor, be
affected after the slabs are inserted.�
24� Find the current I1 and I2 in the respective arms and potential difference across each cell as 3�
shown in fig below: �

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OR�
Find the resistance between two terminals A and C. Each of the resistances in the network
shown in fig equals R. �
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25.� A point object is placed at a distance of 12 cm on the principal axis of a convex lens of focal 3�
length 10cm. A convex mirror is placed coaxially on the other side of the lens at a distance of
10cm. If the final image coincides with the object draw the ray diagram and find the focal
length of the convex mirror.�
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c 26.� A ray of light passes through an equilateral glass prism, such that theseangle
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equal to the angle of emergence. If the angle of emergence is ¾ times
Calculate the refractive index of the glass prism.�
27.� a)� Show the graphical representation of potential energy of a pair of nucleons as a function of 3�
their separation. �
b)� Write two important conclusions which you can draw regarding the nature of nuclear forces. �
The binding energy per nucleon graph peaks at iron-56. Explain the significance of this peak
and how it relates to the processes of nuclear fission and fusion. �
28� (a) In an experiment on scattering of α-particles by a gold nucleus, the closest distance of 3�

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approach is 30 fermi. If the velocity of the α-particle is doubled, then what will be the new

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closest distance of approach?�

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(b)The ground state energy of hydrogen atom is -13.6 eV. What is the potential and kinetic

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energy of an electron in the third excited state.�
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Case Study Based Questions�
Questions number 29 and 30 are case study based questions. Read the following paragraphs and answer
the questions that follow.�
29� � 4�
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The total internal reflection of the light is used in
polishing diamonds to create a sparking brilliance.
By polishing the diamond with specific cuts, it is
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adjusted the most of the light rays approaching the

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surface are incident with an angle of incidence

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more than critical angle. Hence, they suffer multiple reflections and ultimately come out of

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diamond from the top. This gives the diamond a sparking brilliance. �
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(i)Light cannot easily escape a diamond without multiple internal reflections. This is because: �
(a) Its critical angle with reference to air is too large.�
(b) Its critical angle with reference to air is too small.�
(c) The diamond is transparent.�
(d) Rays always enter at angle greater than critical angle.�
(ii)The critical angle for a diamond is 24.40 ,then its refractive index is �

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(a) 2.42 (b) 0.413 (c) 1 (d) 1.413 �

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(iii) The basic reason for the extraordinary sparkle of suitably cut diamond is that �

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(a) It has low refractive index (b) It has high transparency �

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(iv) A diamond is immersed in a liquid with a refractive index greater than water. Then the

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(a) will depend on the nature of the liquid (b) decrease �
(c) remains the same (d) increase�
30� Bohr’s model explains the spectral lines of hydrogen atomic emission spectrum. While an 4�
electron of the atom remains in the ground state, it’s energy is unchanged. When the atom
absorbs one or more quanta of energy, the electron moves from the ground state orbit to an
excited state orbit that is further away. During transition of electron from outer to inner orbit
emits photons with different energy by depending on principal quantum number of outer and

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(i)The above diagram shows an energy level of an atom and several transitions. Which of them
will result in the transition of a photon of wavelength 275 nm? 2�
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(ii)Which transition corresponds to emission of radiation of maximum and minimum
wavelength and why ? 1�
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(iii)Calculate the ratio of maximum to minimum wavelength in Paschen series? 1�
SECTION-E�
31. � (a) Define Gaussian surface.� 5�
(b)Use Gauss’s law to derive the expression for the electric field (E) due to a straight uniformly
� charged infinite line of charge density λ C/m. �
(c) Draw a graph to show the variation of E with perpendicular distance r from the line of
charge. �
OR�
(a) Derive an expression for the electric field E due to a dipole of length ‘2a’ at a point distant
r from the centre of the dipole on the axial line �
(b) Draw a graph of E versus r for r>>a. �
(c) If this dipole is kept in a uniform external electric field Eo, diagrammatically represent the
position of the dipole in stable and unstable equilibrium with condition of equilibrium.�
32. � A parallel plate capacitor is charged by a battery V. After sometime the battery is disconnected 5�
and a dielectric slab with its thickness equal to the plate separation is inserted between the
plates. How will�
(a)The capacitance of the capacitor, �
(b) Electric field between the plates and �
(c) The energy stored in the capacitor be affected? Justify your answer in each case.�
OR�
a) Write two properties of equipotential surfaces. Depict equipotential surfaces due to an
isolated point charge. Why do the equipotential surfaces get closer as the distance between the
equipotential surface and the source charge decreases?�
(b) An electric dipole of dipole moment p, is placed in a uniform electric field E. Deduce the
expression for the torque acting on it.�
33.� (a) Draw a ray diagram showing the image formation by a compound microscope. � 5�
Obtain expression for total magnification when the image is formed at least distance of
distinct vision. �
(b) A compound microscope consists of an objective of 10X and an eyepiece of 20X.
calculate the magnification of microscope.�
OR�
μ2 μ1 μ2 −μ1
(a) Prove the relation − = �
𝑣 𝑢 𝑅
when refraction occurs from rarer to denser medium at convex spherical refracting surface
and image formed is real. Here 𝜇1 and 𝜇2 are the refractive indices of rarer and denser
medium.�
(b) Light from a point source in air falls on a spherical glass having µ = 1.5 and R =0.2 m.
The image is formed at a distance of 100 cm from the glass surface in the direction of incident
light. Calculate the object distance from the centre of curvature of spherical surface.�
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