Class 12 Sample Paper 2023 Physics (Hindi Medium)

Class 12 Sample Paper 2023 Physics

Annual Exam (Practice Paper)
Class: XII:Session: 2022-2023
subject-Physics

Maximum Marks: 70 Marks Time Allowed: 3 hours

General Instructions:
(1) All questions are compulsory. There are 35 questions in all.
(2) This question paper has five sections: Section A, Section B, Section C, Section
D and Section E.
(3) Section A contains15 MCQ and 3 assertion reasoning MCQs of 1 mark each.
Section B contains 7 short answer questions of 2 marks each.
Section C has five short answer questions of 3 marks each .
Section D contains three long answer questions of 5 marks each.
Section E has two case based questions of 4 marks each.
(4) There is no overall choice. However internal choice is provided. You have to
attempt only one of the choices in such questions.

S.No. Section – A Marks

1 Physical quantity which has its S.I unit Coulomb-metre is- 1
a. Electric flux
b. Electric field Intensity
c. Electric potential
d. Electric dipole moment

2 In a parallel plate capacitor, the capacity increases if- 1
a. Area of the plate is decreased.
b. Area of the plate is increased.
c. Distance between the plates increases.
d.Charge stored by capacitor decreases.

3 Which of the following is non-ohmic resistance? 1
a. Diode
b. Copper wire
c. Carbon resistor
d. Silver wire

4 What happens to the magnetic field at the centre of a circular current 1
carrying coil if we double the radius of the coil keeping the current
unchanged?

a. Halved
b. doubled
c. tripled
d. Four times

5 Three needles N1, N2 and N3 are made of a ferromagnetic, a 1
paramagnetic and a diamagnetic substance respectively. A magnet,
when brought close to them, will
а. attract all three of them.
b. attract N1 strongly, but repel N2 and N3 weakly
c. attract N1 and N2 strongly but repel N3.
d. attract N1 strongly, N2 weakly and repel N3 weakly.

6 Relative permeability of a material μr =0.5.The magnetic material is- 1
a. Paramagnetic
b. Ferromagnetic
c. Diamagnetic
d. None of the above

7 The increasing current flows from A to B is as shown in the figure. 1
The direction of the induced current in the loop is-

a. clockwise.
b. anticlockwise.
c. no direction as current will not be induced
d. direction of induced current changes every second

8 The potential at point A is -500 V and that at another point B is 1
+ 500V.The magnitude of work done by an external agent to take 2
units(S.I) of negative charge from B to A will be-
a. 1000 J
b. 3000 J
c. 2000 J
d. 500 J

9 A charge + q is sent into a magnetic field.The force acting on it will 1
be maximum when the angle between the direction of motion of the
charge +q and the magnetic field is-

a. 90°
b. 45°
c. 60°
d. 0°

10 A diffraction pattern is obtained using a beam of red light. What 1
happens if the red light is replaced by blue light?
a. Diffraction pattern becomes broader and apart from the
earlier one.
b. Diffraction pattern becomes narrower and crowded together.
c. Diffraction band disappears.
d. There is no change in diffraction pattern.

11 The direction of ExB in an electromagnetic wave is 1
a. Same as E
b. Same as the direction of propagation of electromagnetic waves.
c. Same as B
d. Opposite to E

12 Work functions of three metals A, B and C are 1.92 eV, 2.0 eV and 1
5.0 eV respectively.If a light of wavelength 4100 Å is incident on the
metals then
a. photoelectrons are emitted from A.
b. photoelectrons are emitted from B.
c. photoelectrons are emitted from C.
d. photoelectrons are emitted from A & B metals.

13 In Bohr’s model, the atomic radius of the first orbit is r0. Then, the 1
radius of the third orbit is-
a. r0
b. 9r0
c. r0/3
d. 3r0

14 The power of a concave lens is 12 D and that of a convex lens is 1
8 D. When these two lenses are placed in contact with each other,
the power of their combination will be -
a. +16D
b. +4 D
c. -16D
d. - 4D

15 Light energy emitted by star is due to 1
a. Nuclear fusion
b. Nuclear fission
c. Nucleus decay
d. Dispersion of light

Directions: These questions consist of two statements, each
printed as Assertion and Reason. While answering these
questions, you are required to choose any one of the following
four responses.
(a) If both Assertion and Reason are correct and the Reason
is a correct explanation of the Assertion.
(b) If both Assertion and Reason are correct but Reason is not
a correct explanation of the Assertion.
(c) If the Assertion is correct but Reason is incorrect.
(d) If both the Assertion and Reason are incorrect.

16 Assertion : Thin film such as soap bubbles or a thin layer of 1
oil on water show beautiful colours when illuminated by white
light.
Reason : It happens due to the interference of light reflected
from the upper and lower face of the thin film.

17 Assertion :A photon and electron have the same de-Broglie 1
wavelength.Photon is moving faster.
Reason :An electron must have velocity less than the speed
of light.

18 Assertion : When two semi conductors of p and n type are 1
brought in contact at atomic level they form a p-n junction
diode ,which is used in the rectifier.
Reason : A rectifier is used to convert alternating current into
direct current.

Section – B

19 a) How does the frequency of a beam of ultraviolet light change, 2
when it goes from air into glass?

b) The capacitor has been charged by a dc source. What are
the magnitudes of conduction and displacement currents,

when it is fully charged?

20 Draw a plot showing the variation of (i) electric field (E) and 2
(ii)electric potential (V) with distance ( r) due to a point charge Q.

OR
Plot the electric field lines around a system of
(i) two positive charges (q, q)
(ii) two equal and opposite charges (q, –q), a dipole.

21 Why are pole pieces of galvanometer made concave? 2
OR
Why does an ammeter have a low resistance?

22 Explain briefly, with the help of circuit diagram, the working of a full 2
wave rectifier. Draw its input and output waveforms.

23 a) Draw the plot of binding energy per nucleon (BE/A) as a function 2
of mass number A.
b)Use this graph to explain the release of energy in both the
processes of nuclear fusion and fission.

24 Suppose that the lower half of the concave mirror reflecting surface 2
is covered with an opaque (non-reflective) material. What effect will
this have on the image of an object placed in front of the mirror?

25 Deduce the expression for the fringe width in Young’s double slit 2
experiment to produce an interference pattern due to a
monochromatic source of light.

Section – C

26 Explain,using a labelled diagram, the principle and working of a 3
moving coil galvanometer.

27 Figures (i),(ii) and (iii) below show planar loops of different shapes 3
moving out of or into a region of a magnetic field which is directed
normal to the plane of the loop away from the reader. Determine
the direction of induced current in each loop using Lenz’s law.
Justify each answer.

OR
A pair of adjacent coils has a mutual inductance of 1.5H. If the
current in one coil changes from 0 to 20A in 0.5 sec, what is the
change of flux linkage with the other coil?

28 a) Draw a graph showing the variation of photocurrent vs 3
collector plate potential for a photosensitive metal of three
different values of frequencies of incident radiation v1, v2 and
v3 (v1 > v2 > v3) for constant intensity.
b) Also draw graph for three different values of intensities of
incident radiation I1, I2 and I3 (I1 > I2 > I3) having same
frequency, showing the variation of photocurrent vs collector
plate potential
c) The maximum kinetic energy of a photoelectron is 3 eV. What
is its stopping potential?

29 It is found experimentally that 13.6 eV energy is required to separate 3
a hydrogen atom into a proton and an electron. Compute the orbital
radius and the velocity of the electron in a hydrogen atom.
Or
A difference of 2.3 eV separates two energy levels in an atom. What
is the frequency of radiation emitted when the atom makes a
transition from the upper level to the lower level?

30 Draw a labelled diagram of a telescope when the image is formed at 3
the least distance of distinct vision.

Hence derive the expression for its magnifying power.

31 5
a) Using Gauss law, derive an expression for the electric field
intensity at any point outside a uniformly charged thin spherical shell
of radius R and charge density 𝜎 C/m^2.
b) A uniformly charged conducting sphere of 2x5 m in diameter has
a surface density of 100 mC/m^2 . Calculate the (i) charge on the
sphere(ii) total electric flux passing through the sphere.

OR
a) Find an expression for the torque acting on an electric dipole
placed in a uniform electric field.
b) A system has two charges qA = 2.5 × 10^−7 C and
qB=−2.5×10^−7C located at points A(0,0,−15cm)and
B(0,0,+15cm),respectively.What are the total charge and
electric dipole moments of the system?

32 a) State the two Kirchhoff’s laws.Explain briefly,how these rules 5
are justified ?

b) The current is drawn from a cell of emf E and internal
resistance r connected to the network of resistors each of resistance
r as shown in the figure.Obtain the expression for
(i) the current drawn from the cell and
(ii) the power consumed in the network

OR
a) A cell of emf 'E' and internal resistance 'r' is connected
across a variable load resistor R. Draw the plots of the
terminal voltage V versus (i) R and (ii) the current I.
b) It is found that When R=4Ω, the current is 1 A and when R is
increased to 9Ω, the current reduces to 0.5 A. Find the values
of the emf E and internal resistance r.

33 a) Draw a labelled diagram of an ac generator. 5
b) Obtain the expression for the emf induced in the rotating coil of N

turns each of cross-sectional area A, in the presence of a magnetic

field
c) A horizontal conducting rod 10 m long extending from east to
west is falling with a speed 5.0 ms^-1 at right angles to the
horizontal component of the Earth’s magnetic field, 0.3 × 10^-4 Wb
m^-2. Find the instantaneous value of the emf induced in the rod.

OR
a) Obtain an expression for the self inductance of a straight
solenoid of length and radius r (l>>r)

b) Distinguish among resistance,reactance and impedance.

c) Two concentric circular coils, one of small radius r 1 and the
other of large radius r 2 , such that r 1 << r 2 , are placed coaxially
with centres coinciding. Obtain the mutual inductance of the
arrangement.

Section – E
Questions 34 and 35 are case study based questions. In case of
internal choice, attempt only one of them.

34 Optical Fibres: 4
Nowadays optical fibres are extensively used for transmitting audio
and video signals through long distances. Optical fibres are
fabricated with high quality composite glass/quartz fibres. Each fibre
consists of a core and cladding. Optical fibres are fabricated such
that light reflected at one side of the inner surface strikes the other
surface at an angle larger than the critical angle. Even if the fibre is
bent, light can easily travel along its length.Thus, an optical fibre can
be used to act as an optical pipe.

1. Optical fibres make use of the phenomenon of-
a) Refraction
b) Total internal reflection
c) Diffraction
d) Polarisation

2. The refractive index of the material of the core of Optical fibre -

a) Is same as of cladding
b) is higher than that of the cladding
c) is lower than that of the cladding
d) refracting index of core or cladding will not affect functioning
of optical fibre.

3. Light reflected at one side of the inner surface strikes the other
surface when-
a) The angle of incidence greater than the critical angle
b) The angle of incidence smaller than the critical angle
c) The angle of incidence equal to the critical angle
d) none of the above
OR
The main requirement in fabricating optical fibres is,there should be:
a) very little absorption of light as it travels for long distances
inside them.
b) High absorption of light as it travels for long distances inside
them.
c) Moderate absorption of light
d) Very high absorption of light

35 semiconductor doped with pentavalent impurity, electrons become 4
the majority carriers and holes the minority carriers. These
semiconductors are, therefore, known as n-type semiconductors.
For n-type semiconductors, we have, ne >> nh.

p-type semiconductor-
Extrinsic semiconductors doped with trivalent impurity are called
p-type semiconductors. For p-type semiconductors, the
recombination process will reduce the number (ni )of intrinsically
generated electrons to (ne).
We have, for p-type semiconductors nh >> ne

1.The conductivity of intrinsic semiconductor increases with

a. increase in temperature
b. decrease in temperature
c. No change in temperature
d. None of the above

2. Doping in semiconductor means
a) Addition of very large amounts of certain specific impurity
atoms.
b) Addition of large amounts of certain specific impurity atoms.
c) Addition of very small amounts of certain specific impurity
atoms.
d) Doping does not mean adding any amounts of certain specific
impurity atoms.

3. The doping of an intrinsic semiconductor with certain type of
impurity atoms causes —-----------in its electric conductivity-
a) Increase
b) Decrease
c) No change
d) Cease
OR
When a battery is connected to a p-type semiconductor with metallic
wire,the current in semiconductor is predominantly due to—----------
a. Holes
b. Electrons
c. Some other charge carriers
d. All of the above