CBSE 12 Physics Question Paper-2022 Set-4 by Pavan | Practice Test to Test Your Knowledge
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  3. CBSE 12 Physics Question Paper-2022 Set-4
CBSE 12 Physics Question Paper-2022 Set-4

CBSE 12 Physics Question Paper-2022 Set-4

This mock test includes actual CBSE Class 12 Physics board exam questions from the year 2022 Set-4, helping students understand exam trends and practice real paper format

2025-08-14
Pavan Pavan
CBSE Physics 2022 Grade 12 Class 12

Duration

36 min

Questions

36

Marking

Negative

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Questions Preview

What is the significance of doping an intrinsic semiconductor? Name the two types of atoms used for doping Ge/Si.

A
Doping decreases the conductivity. The two types of atoms are those with 3 valence electrons and 5 valence electrons.
B
Doping increases the conductivity. The two types of atoms are those with 3 valence electrons (p-type) and 5 valence electrons (n-type).
C
Doping makes the semiconductor an insulator. The two types of atoms are noble gases and halogens.
D
Doping has no effect on conductivity. The two types of atoms are metals and non-metals.

What are the two main conclusions from the Geiger-Marsden experiment, based on the graph of the number of scattered alpha particles (N) vs. scattering angle (θ)?

A
Most of the atom's volume is empty, and the positive charge and mass are concentrated in a small nucleus.
B
The positive charge is distributed uniformly throughout the atom, and the electrons are scattered randomly.
C
The nucleus contains both protons and neutrons, and the electrons orbit it in discrete energy levels.
D
Most of the atom's mass is concentrated in a nucleus, and the electrons are in stable orbits.

Write the characteristics of a p-n junction which make it suitable for rectification.

A
It amplifies the input signal in both forward and reverse bias.
B
It allows current to flow in one direction (forward bias) and blocks it in the opposite direction (reverse bias).
C
It conducts current equally in both forward and reverse bias.
D
It offers high resistance in forward bias and low resistance in reverse bias.

Define the terms: 'impact parameter' and 'distance of closest approach' for an a-particle in Geiger-Marsden scattering experiment. What will be the value of the impact parameter for scattering angle (I) θ=0° and (II) θ=180°?

A
Impact parameter is the perpendicular distance of the initial velocity vector of the alpha particle from the center of the nucleus. The distance of closest approach is the minimum distance between the alpha particle and the nucleus. For θ=0°, b is zero and for θ=180°, b is maximum.
B
Impact parameter is the perpendicular distance of the initial velocity vector of the alpha particle from the center of the nucleus. The distance of closest approach is the minimum distance between the alpha particle and the nucleus. For θ=0°, b is maximum and for θ=180°, b is zero.
C
Impact parameter is the angle of scattering. The distance of closest approach is the maximum distance between the alpha particle and the nucleus. For both θ=0° and θ=180°, b is zero.
D
Impact parameter is the distance between the alpha particle and the nucleus at any point in time. The distance of closest approach is the maximum distance. For θ=0°, b is zero and for θ=180°, b is maximum.

A point source in air is kept 24 cm in front of a concave spherical glass surface (aμg=1.5) and radius of curvature 60 cm. Find the nature of the image formed and its distance from the point source.

A
Real image, 6 cm from the source.
B
Virtual image, 6 cm from the source.
C
Real image, 30 cm from the source.
D
Virtual image, 30 cm from the source.

Calculate the energy released in MeV in the following reaction: H-2 + H-3 -> He-4 + n. Given: m(H-2)=2.014102 u, m(H-3)=3.016049 u, m(He-4)=4.002603 u, mn=1.008665 u.

A
18.234 MeV
B
16.892 MeV
C
17.589 MeV
D
19.121 MeV

Explain with the help of a suitable diagram, the phenomenon on which an optical fibre works. Mention any two uses of optical fibres.

A
Refraction
B
Total Internal Reflection (TIR)
C
Diffraction
D
Interference

A parallel beam of light of wavelength 600 nm is incident normally on a slit of width 0.2 mm. If the resulting diffraction pattern is observed on a screen 1 m away, find the distance of (i) first minimum, and (ii) second maximum, from the central maximum.

A
3 mm, 7.5 mm
B
3 mm, 6 mm
C
6 mm, 7.5 mm
D
6 mm, 3 mm

Photoelectrons are emitted from a metal surface when illuminated with UV light of wavelength 330 nm. The minimum amount of energy required to emit the electrons from the surface is 3.5×10⁻¹⁹ J. Calculate: (i) the energy of the incident radiation, and (ii) the kinetic energy of the photoelectron.

A
Energy: 2.527×10⁻¹⁹ J, KE: 6.027×10⁻¹⁹ J
B
Energy: 6.027×10⁻¹⁹ J, KE: 3.5×10⁻¹⁹ J
C
Energy: 3.5×10⁻¹⁹ J, KE: 2.527×10⁻¹⁹ J
D
Energy: 6.027×10⁻¹⁹ J, KE: 2.527×10⁻¹⁹ J

State the working principle of an LED. Write any two important advantages and two disadvantages of LED.

A
Electroluminescence
B
Photoelectric effect
C
Total Internal Reflection
D
Thermionic emission

Monochromatic light is incident on a surface separating two media. The frequency of the light after refraction remains unaffected but its wavelength changes. Why? The frequency of an electromagnetic radiation is 1.0×10¹¹ Hz. Identify the radiation and mention its two uses.

A
The speed of light remains constant, but the frequency changes.
B
The frequency changes but the wavelength remains constant.
C
The frequency is a property of the source and the speed of light changes in the new medium.
D
The frequency and wavelength both change upon refraction.

Which pair of waves from two sources S₁ and S₂ will produce interference?

A
(i) y₁ = a sinωt and (ii) y₂ = a sin2ωt
B
(ii) y₂ = a sin2ωt and (iii) y₃ = a sin(2ωt+φ)
C
(iii) y₃ = a sin(2ωt+φ) and (iv) y₄ = a sin(4ωt+π/2)
D
(iv) y₄ = a sin(4ωt+π/2) and (i) y₁ = a sinωt

Explain the formation of depletion layer and barrier potential in a p-n junction diode.

A
Due to the accumulation of mobile charges at the junction.
B
Due to the recombination of electrons and holes creating immobile ions at the junction.
C
Due to the external voltage applied across the junction.
D
Due to the repulsion between electrons on the n-side and holes on the p-side.

Ultra-violet light of wavelength 200 nm from a source is incident on a metal surface. If the stopping potential is -2.5 V, (a) calculate the work function of the metal, and (b) How would the surface respond to a high intensity red light of wavelength 6328 Å produced by a laser?

A
Work function: 3.7 eV, Photoelectrons will be emitted.
B
Work function: 2.5 eV, Photoelectrons will be emitted.
C
Work function: 3.7 eV, No photoelectrons will be emitted.
D
Work function: 2.5 eV, No photoelectrons will be emitted.

Find the ratio of the longest and the shortest wavelength in Lyman series in hydrogen atom.

A
3/4
B
4/3
C
2
D
1/2

Find the two possible positions of an object kept in front of a lens of + 5.0 D, so that the image formed in both cases is four times magnified.

A
+15 cm and +25 cm
B
-15 cm and +25 cm
C
-15 cm and -25 cm
D
+15 cm and -25 cm

Plot suitable graphs to show the variation of photoelectric current with the collector plate potential for the incident radiation of (i) the same intensity but different frequencies v₁, v₂, and v₃ (v₁

A
The stopping potential is independent of intensity and increases with frequency. Saturation current increases with intensity and is independent of frequency.
B
The stopping potential increases with intensity and is independent of frequency. Saturation current increases with intensity and frequency.
C
The stopping potential is independent of intensity and frequency. Saturation current increases with intensity and is independent of frequency.
D
The stopping potential increases with frequency and intensity. Saturation current increases with intensity and is independent of frequency.

A thin equiconvex lens of radius of curvature R made of material of refractive index μ₁ is kept coaxially, in contact with an equiconcave lens of the same radius of curvature and refractive index μ₂(>μ₁). Find: (i) the ratio of their powers, and (ii) the power of the combination and its nature.

A
Ratio of powers: (μ₁-1)/(μ₂-1), Combination power: (μ₁-μ₂) * 2/R, Nature: Diverging
B
Ratio of powers: (μ₂-1)/(μ₁-1), Combination power: (μ₁-μ₂) * 2/R, Nature: Converging
C
Ratio of powers: (μ₁-1)/(μ₂-1), Combination power: (μ₁-μ₂) * 2/R, Nature: Converging
D
Ratio of powers: (μ₂-1)/(μ₁-1), Combination power: (μ₁-μ₂) * 2/R, Nature: Diverging

Trace the path of a ray of light PQ which is incident at an angle i on one face of a glass prism of angle A. It then emerges out from the other face at an angle e. Use the ray diagram to prove that the angle through which the ray is deviated is given by δ = i + e - A. What will be the minimum value of δ if the ray passes symmetrically through the prism?

A
The minimum deviation is given by δₘ = 2i - A
B
The minimum deviation is given by δₘ = i - A
C
The minimum deviation is given by δₘ = e - A
D
The minimum deviation is given by δₘ = A - i

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

A
Due to the accumulation of mobile charges at the junction.
B
Due to the recombination of electrons and holes, creating a region of immobile ions near the junction.
C
Due to the external voltage applied across the junction.
D
Due to the repulsion between electrons on the n-side and holes on the p-side.

When a surface is irradiated with the radiation of frequency (i) v₁ and (ii) v₂, photoelectric emission occurs. The maximum kinetic energy of the emitted electrons in the two cases are K and 2K respectively. Obtain the expression for the threshold frequency of the surface.

A
v₀ = (v₂ - 2v₁)
B
v₀ = (2v₁ - v₂)
C
v₀ = (v₁ + v₂)/3
D
v₀ = 2(v₁ - v₂)

How is an emf generated by a solar cell involving three basic processes? Explain.

A
Generation of e-h pairs due to absorption of light, separation of charges due to electric field of the depletion region, and collection of charges.
B
Heating of the p-n junction, creating a potential difference and generating current.
C
Creating a depletion region by applying an external voltage, leading to the flow of charge.
D
Reflecting light from the surface of the solar cell to create an electric field.

Draw a diagram of a plane electromagnetic wave propagating along the x-axis. Write the expressions for its oscillating electric and magnetic fields. Write three characteristics of electromagnetic waves.

A
The electric and magnetic fields are parallel to each other and to the direction of propagation.
B
The electric and magnetic fields are perpendicular to each other but parallel to the direction of propagation.
C
The electric and magnetic fields are perpendicular to each other and to the direction of propagation. The fields oscillate in phase.
D
The electric and magnetic fields are perpendicular to each other and to the direction of propagation, but they oscillate out of phase.

Write the names of electromagnetic waves produced by the following: (i) Radioactive decay of nuclei, (ii) Welding arc, (iii) Hot bodies. Write one use of each of these waves.

A
Radioactive decay: Gamma rays (used in medicine); Welding arc: Ultraviolet rays (used in water purifiers); Hot bodies: Infrared rays (used in remote controls).
B
Radioactive decay: X-rays; Welding arc: Gamma rays; Hot bodies: Radio waves.
C
Radioactive decay: Visible light; Welding arc: Microwaves; Hot bodies: Gamma rays.
D
Radioactive decay: Infrared rays; Welding arc: X-rays; Hot bodies: Visible light.

Explain the working of a Light Emitting Diode (LED) briefly. Mention its two uses.

A
When a p-n junction is reverse biased, electrons and holes recombine and release energy in the form of light. Used in solar cells and photodiodes.
B
When a p-n junction is forward biased, electrons and holes recombine and release energy in the form of light. Used in indicator lamps and remote controls.
C
When a p-n junction is reverse biased, electrons and holes are pulled apart. Used in voltage regulators and rectifiers.
D
When a p-n junction is forward biased, the depletion region widens. Used in lasers and transistors.

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

A
A full wave rectifier uses one diode and rectifies only half of the input AC cycle.
B
A full wave rectifier uses two diodes. The output is a series of positive pulses for both positive and negative half cycles of the input AC.
C
A full wave rectifier uses four diodes in a bridge circuit. The output is a series of negative pulses.
D
A full wave rectifier uses a single diode. The output is DC with no ripple.

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

A
λ_α/λ_p = 1/4, 1/2, 1/√2
B
λ_α/λ_p = 1/2, 1/√2, 1/√2
C
λ_α/λ_p = 1/4, 1/2, 1/2
D
λ_α/λ_p = 1/2, 1, 1/2

Plot the variation of potential energy of a pair of nucleons with the distance between them. Imagine a nucleus of ${}{26}^{56}Fe$ decaying into two equal fragments of ${}{13}^{28}Al$. Is this decay energetically possible? Justify your answer by calculating the Q-value of the process. Given: m(${}{26}^{56}Fe$) = 55.93494 u, m(${}{13}^{28}Al$) = 27.98191 u.

A
Q-value is positive, so the decay is energetically possible.
B
Q-value is negative, so the decay is not energetically possible.
C
Q-value is zero, so the decay is not energetically possible.
D
Q-value depends on the potential energy curve, and it is not possible to determine from the given masses.

The V-I characteristics of a solar cell is shown in the figure. (a) What do the points P and Q represent? (b) Give the circuit diagram for a solar cell.

A
P represents open-circuit voltage (Voc) and Q represents short-circuit current (Isc).
B
P represents short-circuit current (Isc) and Q represents open-circuit voltage (Voc).
C
P represents the maximum power point and Q represents the minimum power point.
D
P represents the knee voltage and Q represents the breakdown voltage.

Differentiate between isotopes and isobars. Two nuclei have different mass numbers A₁ and A₂. Are these nuclei necessarily isotopes of the same element? Justify your answer.

A
Isotopes have the same number of protons but different mass numbers. Isobars have the same mass number but different numbers of protons. They are not necessarily isotopes of the same element because isotopes must have the same number of protons.
B
Isotopes have the same mass number but different numbers of protons. Isobars have the same number of protons but different mass numbers. They are necessarily isotopes of the same element.
C
Isotopes and isobars are the same thing. They are necessarily isotopes of the same element.
D
Isotopes and isobars both have the same number of protons and neutrons. They are not necessarily isotopes of the same element.

State Bohr's postulate to explain stable orbits in a hydrogen atom. Prove that the speed with which the electron revolves in nth orbit is proportional to (1/n).

A
The speed is proportional to n².
B
The speed is independent of n.
C
The speed is proportional to 1/n.
D
The speed is proportional to n.

(a) Write two necessary conditions for total internal reflection. (b) Two prisms ABC and DBC are arranged as shown in figure. The critical angles for the two prisms with respect to air are 41.1° and 45° respectively.

A
Light must travel from a denser to a rarer medium, and the angle of incidence must be greater than the critical angle.
B
Light must travel from a rarer to a denser medium, and the angle of incidence must be less than the critical angle.
C
Light must travel from a denser to a rarer medium, and the angle of incidence must be less than the critical angle.
D
Light must travel from a rarer to a denser medium, and the angle of incidence must be greater than the critical angle.

An object is placed in front of a converging lens. Obtain the conditions under which the magnification produced by this lens is (i) negative and (ii) positive. A point object is placed in front of a glass sphere as shown in the figure. Show the image formation by this sphere. The work function of a metal is 2.31 eV. Photoelectric emission occurs when light of frequency 6.4 × 10¹⁴ Hz is incident on the metal surface. Calculate : (i) the energy of the incident radiation, (ii) the maximum kinetic energy of the emitted electron and (iii) the stopping potential of the surface.

A
Magnification is negative for a real image and positive for a virtual image. Energy of incident radiation = 2.65 eV, KE = 0.34 eV, Stopping potential = 0.34 V.
B
Magnification is negative for a virtual image and positive for a real image. Energy of incident radiation = 2.31 eV, KE = 0.34 eV, Stopping potential = 0.34 V.
C
Magnification is always positive. Energy of incident radiation = 2.65 eV, KE = 2.31 eV, Stopping potential = 2.31 V.
D
Magnification is always negative. Energy of incident radiation = 2.31 eV, KE = 0.34 eV, Stopping potential = 0.34 V.

A beam of light consisting of two wavelengths 600 nm and 500 nm is used to obtain interference fringes in a Young’s double slit experiment. Find the ratio of the fringe widths of the two waves.

A
5:6
B
6:5
C
1:1
D
2:1

The energy of hydrogen atom in an orbit is -1.51 eV. What are the kinetic and potential energies of the electron in this orbit? An electron in a hydrogen atom is found at a distance of about 5.3 × 10⁻¹¹ m from the nucleus of diameter approximately 1.0 × 10⁻¹⁵ m. Assuming the hydrogen atom to be a sphere of radius 5.3 × 10⁻¹¹ m, what fraction of the volume of the atom is occupied by the nucleus?

A
KE = +1.51 eV, PE = -3.02 eV, Volume fraction ≈ 10⁻¹⁵
B
KE = -1.51 eV, PE = +3.02 eV, Volume fraction ≈ 10⁻¹⁵
C
KE = +1.51 eV, PE = -1.51 eV, Volume fraction ≈ 10⁻¹⁸
D
KE = +3.02 eV, PE = -1.51 eV, Volume fraction ≈ 10⁻¹⁸

Define the term - Distance of closest approach. How will it be affected, for an a particle, if kinetic energy of the particle is doubled ?

A
It will be quadrupled.
B
It will remain the same.
C
It will be doubled.
D
It will be halved.