Wave Phenomena (Reflection, Refraction, Diffraction, Interference) — A/L Physics

Reflection The bouncing back of a wave when it encounters a boundary between two media. The angle of incidence equals the angle of reflection (measured from the normal). For a fixed boundary (e.g., a rigid wall), a reflected pulse inverts (phase change of π). For a free boundary, no inversion occurs. Example: Sound echoing off a cliff; light reflecting from a mirror.

Refraction The change in direction of a wave as it passes from one medium to another due to a change in speed. When a wave enters a medium where its speed decreases (e.g., light from air to glass), it bends toward the normal. If speed increases, it bends away. The frequency remains constant; wavelength changes proportionally to speed. Example: A straw appearing bent in a glass of water.