Science (English Medium) Class 12 - CBSE Important Questions

A partially plane polarised beam of light is passed through a polaroid. Show graphically the variation of the transmitted light intensity with angle of rotation of the polaroid ?

Explain with the help of a diagram how sunlight is polarised by scattering through atmospheric particles ?

A parallel beam of light of wavelength 500 nm falls on a narrow slit and the resulting diffraction pattern is observed on a screen 1 m away. It is observed that the first minimum is a distance of 2.5 mm away from the centre. Find the width of the slit.

What does a polaroid consist of? How does it produce a linearly polarised light?

Explain briefly how sunlight is polarised by scattering through atmospheric particles.

Write two characteristics features distinguish the diffractions pattern from the interference fringes obtained in Young’s double slit experiment.

Two wavelengths of sodium light 590 nm and 596 nm are used, in turn, to study the diffraction taking place due to a single slit of aperture 1 × 10⁻⁴ m. The distance between the slit and the screen is 1.8 m. Calculate the separation between the positions of the first maxima of the diffraction pattern obtained in the two cases.

A parallel beam of light of 450 nm falls on a narrow slit and the resulting diffraction pattern is observed on a screen 1.5 m away. It is observed that the first minimum is at a distance of 3 mm from the centre of the screen. Calculate the width of the slit.

How does the angular separation between fringes in single-slit diffraction experiment change when the distance of separation between the slit screens is doubled?

State the importance of coherent sources in the phenomenon of interference.

In Young’s double slit experiment to produce interference pattern, obtain the conditions for constructive and destructive interference. Hence deduce the expression for the fringe width.

How does the fringe width get affected, if the entire experimental apparatus of Young is immersed in water?

 State Huygen’s principle. Using this principle explain how a diffraction pattern is obtained on a screen due to a narrow slit on which a narrow beam coming from a `=> n = (vlamda)/(vlamda_omega)`monochromatic source of light is incident normally.

If a monochromatic source of light is replaced by white light, what change would you observe in the diffraction pattern?

What is an unpolarized light? Explain with the help of suitable ray diagram how an unpolarized light can be polarized by reflection from a transparent medium. Write the expression for Brewster angle in terms of the refractive index of denser medium.

State Huygens’s principle. Show, with the help of a suitable diagram, how this principle is used to obtain the diffraction pattern by a single slit.

Draw a plot of intensity distribution and explain clearly why the secondary maxima becomes weaker with increasing order (n) of the secondary maxima.

You are given following three lenses. Which two lenses will you use as an eyepiece and as an objective to construct an astronomical telescope?

If the angle between the pass axis of polarizer and the analyser is 45º, write the ratio of the intensities of original light and the transmitted light after passing through the analyser.

In a single slit diffraction experiment, when tiny circular obstacle is placed in path of light from a distance source, a bright spot is seen at the centre of the shadow of the obstacle. Explain why?

Explain how an unpolarised light gets polarised when incident on the interface separating the two  transparent media.