Wavefronts: Reflection, Refraction, Diffraction

A wavefront is an imaginary line or surface joining points on a wave that are in the same phase of vibration. For a set of straight parallel waves, the wavefronts may be drawn as parallel lines.

**Reflection** occurs when a wave meets a boundary and returns into the original medium. The angle of incidence is equal to the angle of reflection: **i = r**

**Refraction is a change in the direction of a wave when its speed changes as it enters a different medium or region. The wave's frequency remains unchanged at the boundary, but speed and wavelength can change. Using: v = fλ** if frequency stays constant and speed changes, wavelength must also change.

**Diffraction** is the spreading of waves when they pass through an opening or around an obstacle. Diffraction is strongest when the gap size is comparable with the wavelength.