CBSE(NCERT) GRADE 12 PHYSICS 2022 SET3

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.

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

(a) (i) Define 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) = 0 and (II) = 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.

(a) Depict the variation of the potential energy of a pair of nucleons with the separation between them. (b) Imagine the fission of a Fe 56 26 into two equal fragments of Al2813nucleus. Is the fission energetically possible ? Justify your answer by working out Q value of the process.

What do the points P and Q represent?

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.

Give the circuit diagram for a solar cell.

An equiconvex lens forms a two times enlarged real image when an object is kept 16 cm from it. The lens is cut into two identical plano-convex lenses. If the object is again kept 16 cm in front of one of these lenses, then find the nature and position of the image formed.

What will be the value of the impact parameter for scattering angle (I) = 0 and (II) = 180?

A ray is incident on a prism of material of refractive index 2 at point M such that it grazes along NC after emerging from the prism, as shown in the figure. Find : (a) the critical angle for the prism. (b) the angle of refraction at face AB.

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.

Depict the variation of the potential energy of a pair of nucleons with the separation between them.

Imagine the fission of a Fe56 26 into two equal fragments of Al28 13 nucleus. Is the fission energetically possible? Justify your answer by working out Q value of the process. Given: m Fe56 26 = 55.93494 u, m Al28 13 = 27.98191 u.

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.

An electron is in the third excited state in a hydrogen atom. It undergoes transitions to the lower energy states. (a) What is the maximum number of spectral lines that can be emitted? (b) Calculate the minimum wavelength of the spectral lines emitted.

(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.

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.

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.

is incident normally on (i) Depict the intensity distribution in the pattern observed. (ii) Obtain the expression for the first maximum from the central maximum.

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 setdouble 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. If the screen is moved closer to the plane of slits S1 and S2, then the fringe width :

What will happen to the pattern on the screen, when the two slits S1 and S2 are replaced by two independent but identical sources ?

Two sources of light are said to be coherent, when both emit light waves of :

The fringe width is β. If the whole set-up is immersed in a liquid of refractive index μ, then the new fringe width will be :

The total path difference between two waves meeting at points P1 and P2 on the screen are λ/2 and 3λ/2 respectively. Then :