Physics · 2022 · Set 55/2/1

CBSE Class 12 Physics 2022 — Set 55/2/1

CBSE Class XII Board 2022 · Set 55/2/1

Real board examination

Sets

About the 2022 exam: 2022 was CBSE's special COVID year: the board exam was split into two terms instead of one 70-mark paper. Term 1 (Dec 2021) was multiple-choice only; Term 2 (2022 — the papers shown here) was a shorter subjective paper of just 12 questions for 35 marks. So the smaller size IS the real exam that year, not missing content — 3 complete series (55/1/1, 55/2/1, 55/4/1) of 12 questions each. Some topics examined then have since been removed from the syllabus — badged and filterable above.

This paper has 1 question on a topic removed in CBSE’s 2023-24 syllabus update (each marked Not in syllabus). It’s kept for historical accuracy — the exam really asked it that year — but isn’t in the current syllabus and doesn’t count toward a concept’s importance. Switch to to focus on what’s still examinable.

About this paper

The real Class-12 board examination held in 2022. Every question below is solved the concept-first way. Sample papers are labelled honestly — never shown as a past exam.

Total marks: 35
Questions: 12
Duration: 120 min
Sections: 3

The marks / questions / duration above are the official exam pattern. We currently have 12 of this paper’s questions (100% of the full paper), with 12 fully solved. Questions we couldn’t yet extract or verify are held — never shown as complete.

Sections & marks

Section	Type	Questions	Marks each	Total
ASection A	Short answer	3	2	6
BSection B	Short answer	8	3	24
CSection C	Case-based	1	5	5
Total		12		35

The question paper

The questions we hold for this paper, laid out by section. Solutions are on the Answers tab.

Board Examination

Physics

CBSE Class XII Board 2022 · Set 55/2/1

Series/Set: 55/2/1Roll No. ________

Time Allowed: 2 hoursMaximum Marks: 35

General Instructions

This question paper contains 12 questions divided into 3 sections — A, B, C.
Section A comprises 3 questions of 2 marks each (Short answer).
Section B comprises 8 questions of 3 marks each (Short answer).
Section C comprises 1 question of 5 marks each (Case-based).

Above is the official exam pattern. The questions printed below are those we currently hold for this paper.

Section A

Short answer · 2 marks each · 3 of 3 shown

Q1.

Explain the formation of depletion region in a p-n junction.

[2]

Q2.

(a)

(i) Define the terms 'impact parameter' and 'distance of closest approach' for an $\alpha$ -particle in Geiger-Marsden scattering experiment.
(ii) What will be the value of the impact parameter for scattering angle (I) $\theta = 0^\circ$ and (II) $\theta = 180^\circ$ ?

(OR)

(b) Photoelectric emission occurs when a surface is irradiated with the radiation of frequency

(i) $\nu_1$ , and
(ii) $\nu_2$ . The maximum kinetic energy of the electrons emitted in the two cases are $K$ and $2K$ respectively. Obtain the expression for the threshold frequency for the surface.

[2]

Q3.

How is an emf generated by a solar cell due to the three basic processes involved ? Explain.

⚠ This question is not in the current syllabus — solar cell (removed 2023-24)

[2]

Section B

Short answer · 3 marks each · 8 of 8 shown

Q1.

(a)

(i) Depict a plane electromagnetic wave propagating along the x-axis. Write the expressions for its oscillating electric and magnetic fields.
(ii) Write three characteristics of electromagnetic waves.

(OR)

(b) Name the electromagnetic waves which are produced by the following :

(i) Radioactive decays of nucleus
(ii) Welding arcs
(iii) Hot bodies Write one use each of these waves.

[3]

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Q2.

(a) State the conditions for total internal reflection to take place. (b) A tank is filled with a transparent liquid to height 'H'. A coin suspended by a thread in the liquid is gradually lowered till it touches the bottom. The apparent depth is determined corresponding to different positions of the coin. (i) Plot a graph showing variation of the apparent depth with the real depth of the coin. (ii) What is the physical significance of the slope of the graph ?

[3]

Q3.

(a) Draw a labelled ray diagram showing the formation of an image by an astronomical refracting telescope in normal adjustment. Hence, obtain the expression for its magnifying power. OR (b) A plane wavefront of light of wavelength 'λ' is incident normally on a narrow slit of width 'a' and a diffraction pattern is observed on a screen at a distance 'D' from the slit. (i) Depict the intensity distribution in the pattern observed. (ii) Obtain the expression for the first maximum from the central maximum.

[3]

Q4.

A converging lens made of glass (μ = 1.5) has its spherical faces of radii of curvature 10 cm and 20 cm. Find its focal length (a) in air, and (b) when it is immersed in a liquid of refractive index 1.25.

[3]

Q5.

The energy of a hydrogen atom in the first excited state is -3.4 eV. Find : (a) the radius of this orbit. (Take Bohr radius = 0.53 Å) (b) the angular momentum of the electron in the orbit. (c) the kinetic and potential energy of the electron in the orbit.

[3]

Q6.

(a) Depict the variation of the potential energy of a pair of nucleons with the separation between them. (b) Imagine the fission of a ⁵⁶₂₆mathrmFe into two equal fragments of ²⁸₁₃mathrmAl nucleus. Is the fission energetically possible ? Justify your answer by working out Q value of the process. Given : m(⁵⁶₂₆mathrmFe) = 55.93494 u, m(²⁸₁₃mathrmAl) = 27.98191 u.

[3]

Q7.

Find the ratio of the de Broglie wavelengths associated with an alpha particle and a proton, if both (a) have the same speeds, (b) have the same kinetic energy, (c) are accelerated through the same potential difference.

[3]

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Q8.

With the help of a circuit diagram, explain the working of a p-n junction diode as a full-wave rectifier. Also draw its input and output waveforms.

[3]

Section C

Case-based · 5 marks each · 1 of 1 shown

Q1.

The British physicist Thomas Young explained the interference of light using the principle of superposition of waves. He observed the interference pattern on the screen, in his experimental set-up, known now as Young's double slit experiment. The two slits S₁ and S₂ were illuminated by light from a slit S. The interference pattern consists of dark and bright bands of light. Such bands are called fringes. The distance between two consecutive bright and dark fringes is called fringe width. (a) If the screen is moved closer to the plane of slits S₁ and S₂, then the fringe width : (i) will decrease, but the intensity of bright fringe remains the same. (ii) will increase, but the intensity of bright fringe decreases. (iii) will decrease, but the intensity of bright fringe increases. (iv) and the intensity both remain the same. (b) What will happen to the pattern on the screen, when the two slits S₁ and S₂ are replaced by two independent but identical sources ? (i) The intensity of pattern will increase (ii) The intensity of pattern will decrease (iii) The number of fringes will become double (iv) No pattern will be observed on the screen (c) Two sources of light are said to be coherent, when both emit light waves of : (i) same amplitude and have a varying phase difference. (ii) same wavelength and a constant phase difference. (iii) different wavelengths and same intensity. (iv) different wavelengths and a constant phase difference. (d) The fringe width in a Young's double slit experiment is β. If the whole set-up is immersed in a liquid of refractive index 'μ', then the new fringe width will be : (i) β (ii) βμ (iii) (β)/(μ) (iv) (β)/(μ²) (e) The total path difference between two waves meeting at points P₁ and P₂ on the screen are ((3λ)/(2)) and 2λ respectively. Then : (i) bright fringes are formed at both points. (ii) dark fringes are formed at both points. (iii) a bright fringe is formed at P₁ and a dark fringe is formed at P₂. (iv) a bright fringe is formed at P₂ and a dark fringe is formed at P₁.

[5]

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