Science (English Medium) Class 12 - CBSE Important Questions for Physics

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.

Green light is incident at the polarising angle on a certain transparent medium. The angle of refraction is 30° . Find
(i) polarising angle, and
(ii) refractive index of the medium.

Can the interference pattern be produced by two independent monochromatic sources of light? Explain.

The intensity at the central maximum (O) in a Young’s double slit experimental set-up shown in the figure is I_O. If the distance OP equals one-third of the fringe width of the pattern, show that the intensity at point P, would equal `(I_0)/4`.

In Young’s double slit experiment, the slits are separated by 0.5 mm and screen is placed 1.0 m away  from the slit. It is found that the 5^th bright fringe is at a distance of 4.13 mm from the 2^nd dark fringe.  Find the wavelength of light used.  

Derive the relation a sin θ = λ  for the first minimum of the diffraction pattern produced due to a single slit of width ‘a’ using light of wavelength λ.

Using the monochromatic light of same wavelength in the experimental set-up of the diffraction pattern  as well as in the interference pattern where the slit separation is 1 mm, 10 interference fringes are found  to be within the central maximum of the diffraction pattern. Determine the width of the single slit, if the  screen is kept at the same distance from the slit in the two cases.

What is the speed of light in a denser medium of polarizing angle 30?

Define the term wavefront. Using Huygen’s wave theory, verify the law of reflection.