Waves - including sound and light - can be reflected at the boundary between two different materials. The reflection of sound causes echoes.

Focusing on easy but scoring topics, clean presentation with well-labelled diagrams wherever necessary, and proper definitions can help achieve good marks, the experts said.

Rule 1: After reflection, a ray of light parallel to the principal axis appears to be coming from focus. Rule 2: A ray of light going towards centre of curvature is reflected back along the same path.

Question The diagram shows a ray of light incident on a glass block. a) At which point would you expect the ray to emerge from the block? [2 marks] b) A ray box is used to produce the ray of light.