Using Huygen.s principle, verify Snell.s law of refraction of plane wave propagating from denser medium to rarer medium.

Huygen.s principle is used

When a wave travels from a denser to rarer medium, then

Use Huygen's principle to show how a plane wavefront propagates from a denser to rarer medium. Hence verift snell's law of refreaction.

Answer the following: (a) What is a wave front? How does it propagate? Using Huygens' principle, explain reflection of a plane wavefront from a surface and verify the laws of reflection. (b) A parallel beam of light of wavelength 500 nm falls on a narrow slit and the resulting diffraction pattern is obtained on a screen 1 m away. If the first minimum is formed at a distance of 2.5 mm from the centre of screen, find the (i) width of the slit, and (ii) distance of first secondary maximum from the centre of the screen.

(I) How does the refractive index of a medium depends on the wavelength of light used? (II)Which is greater, angle of incidence or angle of refraction, when light travels from denser medium to rarer medium.

(a) State Huygen's principle . Using this principle draw a diagram to show how a plane wave front incident at the interface of the media gets refracted when it propagates from a rarer to a denser medium. Hence verify Snell's law of refraction. (b) When monochromatic light travels from a rarer to a denser medium, explain the following, giving reasons- (i) Is the frequency of reflected and refracted light same as the frequency of incident light? (ii) Does the decrease in speed imply a reduction in the energy carried by light wave?

Answer the following: (a) Define wavefront. Use Huygens' principle to verify the laws of refraction. (b) 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 is 1.5 .