Class 12 Physics 2022 Board Exam

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

The V – I characteristics of a solar cell is shown in the figure.
(a) What do the points P and Q represent ?

Give the circuit diagram for a solar cell.

(b) Photoelectric emission occurs when a surface is irradiated with the radiation of frequency (i) v₁, and (ii) v₂. 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.

Distinguish between nuclear fission and fusion.

The mass defect in a nuclear fusion reaction is 0.05%. What amount of energy will be liberated in one kg of fusion reaction ?

Briefly explain the working of a light emitting diode. Mention its two uses.

Define the term 'intensity' of radiation in photon picture of light.

Plot a graph showing the variation of photocurrent vs collector potential for three different intensities I₁ > I₂ > I₃ of incident radiation having same frequency v > v₀.

(a) (i) Define the terms : 'impact parameter' and 'distance of closest approach' for an α-particle in Geiger-Marsden scattering experiment. (ii) What will be the value of the impact parameter for scattering angle (I) θ = 0° and (II) θ = 180° ?
OR
(b) Photoelectric emission occurs when a surface is irradiated with the radiation of frequency (i) v₁, and (ii) v₂. 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.