Reflection, refraction, and diffraction

Waves change direction in three main ways. In reflection, a wave bounces off a surface, and the angle of incidence equals the angle of reflection, both measured from the normal, a line perpendicular to the surface; echoes and mirror images come from reflection. In refraction, a wave bends as it passes into a new medium where its speed changes: light slows down entering water and bends toward the normal, which is why a straw in a glass of water looks bent. In diffraction, a wave spreads out as it passes through an opening or around an obstacle, and the effect is strongest when the opening is about the same size as the wavelength; that is why you can hear someone talking around a corner even though you cannot see them, since sound's wavelengths are much longer than light's.

This explanation is AI-generated and can occasionally be wrong. 🚩 Report