In Young's double-slit experiment, light of wavelength 600 nm falls on slits 1 mm apart and the screen is 1 m away. Find the fringe width.

What is polarisation, and what does it prove about the nature of light?

State Huygens' principle and use it to explain refraction qualitatively.

State the conditions for sustained interference of light.

Distinguish between interference and diffraction of light.

In a double-slit experiment the fringe width is 0.5 mm. What happens to it if the whole apparatus is immersed in water of refractive index 4/3?

State Kirchhoff's two laws and say what conservation principle each expresses.