Science (English Medium) इयत्ता १२ - CBSE Important Questions for Physics

What dose a polaroid consist of?

Monochromatic light of frequency 6.0 × 10¹⁴ Hz is produced by a laser. The power emitted is 2.0 × 10⁻³ W. Estimate the number of photons emitted per second on an average by the source

In what way is diffraction from each slit related to the interference pattern in a double-slit experiment?

Draw the intensity pattern for single slit diffraction.

Draw the intensity pattern for double slit interference.

State differences between interference and diffraction patterns.

Unpolarised light is passed through a polaroid P₁. When this polarised beam passes through another polaroid P₂ and if the pass axis of P₂ makes angle θ with the pass axis of P₁, then write the expression for the polarised beam passing through P₂. Draw a plot showing the variation of intensity when θ varies from 0 to 2π.

Use Huygens' principle to verify the laws of refraction.

How is linearly polarised light obtained by the process of scattering of light. Find the Brewster angle for air – glass interface, when the refractive index of glass = 1.5. 

When light travels from a rarer to a denser medium, the speed decreases. Does this decrease in speed imply a reduction in the energy carried by the wave?

In the wave picture of light, the intensity of light is determined by the square of the amplitude of the wave. What determines the intensity in the photon picture of light?

The value of Brewster's angle for a transparent medium is different for light of different colours. Give reason.

Distinguish between unpolarised and linearly polarised light.

Write three characteristic features to distinguish between the interference fringes in Young's double slit experiment and the diffraction pattern obtained due to a narrow single slit.

Two wavelengths of sodium light 590 nm and 596 nm are used, in turn to study the diffraction taking place at a single slit of aperture 2 × 10⁻⁴m. The distance between the slit and the screen is 1.5 m. Calculate the separation between the positions of the first maxima of the diffraction pattern obtained in the two cases.

 Define  refracting telescope magnifying power and write the expression for it ?

In Young's double slit experiment, derive the condition for

(i) constructive interference and

(ii) destructive interference at a point on the screen.

A beam of light consisting of two wavelengths, 800 nm and 600 nm is used to obtain the interference fringes in a Young's double slit experiment on a screen placed 1 · 4 m away. If the two slits are separated by 0·28 mm, calculate the least distance from the central bright maximum where the bright fringes of the two wavelengths coincide.

How does an unpolarized light incident on a polaroid get polarized? Describe briefly, with the help of a necessary diagram, the polarization of light by reflection from a transparent medium.

Two polaroids ‘A’ and ‘B’ are kept in crossed position. How should a third polaroid ‘C’ be placed between them so that the intensity of polarized light transmitted by polaroid B reduces to 1/8^th of the intensity of unpolarized light incident on A?