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.

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

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.

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.

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.