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.

Unpolarised light is incident on two polarizing sheets placed over one another. The intensity of light transmitted finally is one-third of the intensity of the incident light. Calculate the angle between the transmission axes of the two polarizing sheets.

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.

Explain the propagation of light through optical fibre. What are the advantages of

using optical fibres for communication?

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.

Discuss the opponent-process theory of colour vision.

Compare and contrast three level and four level pumping schemes.