Class 12 Sample Paper 2022 Solution Physics Term 2

Suggestive Solutions
Practice paper term – 2
Class – XII
Physics (Code: 042)

खंड - अ
SECTION – A
प्र. स.
Q. No.
Q1 a) Correct two differences between n-type and p-type semiconductor.

b) Depletion region or depletion layer is a region in a P-N junction diode where
no mobile charge carriers are present. Depletion layer acts like a barrier that
opposes the flow of electrons from n-side and holes from p-side.

Q2 Correct derivation with steps

OR

a) Bohr's quantisation condition: an electron can revolve only in certain
discrete, non-radiating orbits for which total angular momentum of
the

revolving electron is an integral multiple of h/ 2 π where h is the
Planck's constant.

i.e L= mvr = nh/2 π

b)The Rydberg's formula for the hydrogen atom is

Q3 a) Solar cell
b) P point shows open circuit voltage ,Q point shows short circuit
circuit

c) The energy band gap for Si is about 1.1eV, while for GaAs, it is
about 1.53eV. The GaAs and Si absorb relatively more energy
from the incident solar radiation being of relatively higher
absorption coefficient.

खंड – ब
SECTION – B
Q4 Mass of the bullet, m = 0.040 kg

Speed of the bullet, v = 1.0 km/s = 1000 m/s

Planck’s constant, h = 6.6 × 10−34 Js

De Broglie wavelength of the bullet is given by the relation: λ = h/mv

= 6.6 x 10-34 / 0.040 x 1000 = 1.65 x 10-35 m

Mass of the ball, m = 0.060 kg

Speed of the ball, v = 1.0 m/s

De Broglie wavelength of the ball is given by the relation: λ = h/mv

= 6.6 x 10-34 / 0.060 x 1 = 1.1 x 10-32 m

ball is having more wavelength than bullet.

Q5 a) Total internal reflection

b) Following are the two conditions for the total internal reflection to take
place:
1) The angle of incidence in the denser medium must be greater than
the critical angle for that pair of media.
2) The ray of light must travel from a denser medium into a rarer
medium

c) n = 1 / sin C = 1/sin30º = 2

Speed of light in medium v = c/n = (3 x108 ) / 2

= 1.5 x 108 m/s

Q6 a) Diode D1 is forward biased and diodeD2 is reverse biased.

b) D2 is in reverse bias so no current through it.

Now I = ε / R = 6 / 2+1 = 2A
c) Correct two differences

Q7 a) The descending order of frequencies: red light, x-rays, microwaves, radio
waves are given as:
X-rays > Red light >Microwaves >Radio Waves
b) The waves used in radar are microwaves.
c) The main role of the ozone layer in the atmosphere is that it absorbs all
harmful UV rays and protect us from their harmful effects.

Q8
a) (i) point source : spherical wave front
(ii) Distant light source: plane wave front
b) Correct definition of coherent sources
c) There is no change in speed of light and wave length when a wave
gets reflected from a given surface .

OR

a)Coherent sources have a constant phase difference. This ensures that the
position of Maxima and minima do not change with time i.e., a sustained
interference pattern is obtained.

b)This happens because, the intensity of central maximum is due to wavelets
from all parts of the slit. First secondary maxima is formed due wavelets from
one third parts of the slit and second secondary maxima is due to wavelets
from one fifth part of the slit and so on. This is the reason why intensity of
secondary maxima becomes less as compared to central maxima.

c)

Q9 a) Correct two differences between nuclear fission and nuclear fusion.
b) The ratio of their nuclear densities is 1:1, as nuclear density is
constant for all nuclei.

Q 10

Q11 a) Reflection and refraction arise through interaction of incident light with
the atomic constituents of matter. Atoms may be viewed as oscillators,
which take up the frequency of the external agency (light) causing
forced oscillations. The frequency of light emitted by a charged
oscillator equals its frequency of oscillation. Thus, the frequency of
scattered light equals the frequency of incident light.

(b) No. Energy carried by a wave depends on the amplitude of the wave, not
on the speed of wave propagation.

(c) For a given frequency, intensity of light in the photon picture is determined
by the number of photons crossing an unit area per unit time

OR

खंड – स
SECTION – C

Q12 a) iii
b) i
c) iv

d) iii

(e) iv