Science (English Medium) कक्षा १२ - CBSE Important Questions

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. 

Distinguish between unpolarized and linearly polarized light.

Answer the following question.
Define the term wavefront. Using Huygen's wave theory, verify the law of reflection.

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

Greenlight is an 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.

(a) Can the interference pattern be produced by two independent monochromatic sources of light? Explain.
(b) The intensity at the central maximum (O) in 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 `"I"_°/4`

(c) In Young's double-slit experiment, the slits are separated by 0⋅5 mm and the screen is placed 1⋅0 m away from the slit. It is found that the 5th bright fringe is at a distance of 4⋅13 mm from the 2nd 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 the 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.

Define a wavefront. Using 'Huygens' principle, draw the shape of a refracted wavefront, when a plane wave is incident on a convex lens.

In Young's double-slit experiment, the two slits are separated by a distance of 1.5 mm, and the screen is placed 1 m away from the plane of the slits. A beam of light consisting of two wavelengths of 650 nm and 520 nm is used to obtain interference fringes.
Find the distance of the third bright fringe for λ = 520 nm on the screen from the central maximum.

In Young's double-slit experiment, the two slits are separated by a distance of 1.5 mm, and the screen is placed 1 m away from the plane of the slits. A beam of light consisting of two wavelengths of 650 nm and 520 nm is used to obtain interference fringes.
Find the least distance from the central maximum where the bright fringes due to both the wavelengths coincide.

(a) A ray of light is incident normally on the face AB of a right-angled glass prism of refractive index _aμ_g 1.5. The prism is partly immersed in a liquid of an unknown refractive index. Find the value of the refractive index of the liquid so that the ray grazes along the face BC after refraction through the prism.

(b) Trace the path of the rays if it were incident normally on the face AC.

Choose the correct answer from given options
The relationship between Brewster angle θ and speed of light v in the denser medium is