A ray of light travelling in air strikes a glass surface at an angle of incidence of 60°. If the refractive index of glass is 1.5, find the sine of the angle of refraction.

A tank is filled with water to a depth of 40 cm. If the refractive index of water is 4/3, find the apparent depth of the tank.

The critical angle for a certain medium is 30°. Calculate its refractive index.

State the two conditions necessary for total internal reflection to take place.

Why does a coin at the bottom of a beaker of water appear to be raised?

The refractive index of glass is 1.5 and the speed of light in vacuum is 3 × 10⁸ m s⁻¹. Calculate the speed of light in glass.

Explain how total internal reflection makes an optical fibre able to carry light round bends.