What do you understand by birefringence? What are distinguishing feature of the o−

and e− rays? Draw a diagram showing o− and e−wave surfaces.

What is a zone plate? How does a positive zone plate differ from a negative zone plate? Show that each Fresnel half period zone has nearly the same area

State Fermat’s principle. On the basis of this principle, show that when light passes from a medium of lower refractive index to a medium of higher refractive index, it

bends towards the normal to the interface between the two media.

The diffraction pattern due to a single slit of width 0.4 cm is obtained with the help of a lens of focal length 30 cm. If wavelength of the light used is 589 nm, calculate the distance of the first dark fringe and the consecutive bright fringe from the axis.

A light of amplitude ‘a’ is incident obliquely on a parallel thin film. If ‘r’ and ‘t’ represent the fractions of incident light reflected and transmitted respectively, draw a diagram to explain multiple reflection of incident light and write the amplitudes of successive rays.

A single slit has a width of 0.04 mm. A parallel beam of light of wavelength 560 nm is incident normally on it. If the distance between the slit and the screen is 100 cm, calculate the separation between the central maximum and the second minima in the diffraction pattern.

Sodium light is incident normally on a grating of width 4×10⁻³m. The total number

of lines on the grating is 2000. Determine the angular separation between the sodium

D-lines in the first order spectrum.