CBSE 12 Physics Question Paper-2022 Set-1

Draw energy band diagrams of n-type and p-type semiconductors at temperature T>0K depicting the donor and acceptor energy levels. Mention the significance of these levels.

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)?

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

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 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.

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.

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

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.

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.

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

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.

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

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

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?

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

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.

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 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.

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?