Wavefronts: Reflection, Refraction, Diffraction

Wavefronts: Reflection, Refraction, Diffraction

Reflection is bouncing back.

Refraction is a change in direction when wave speed changes.

Diffraction is spreading around edges or through gaps.

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

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

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

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.

Wavefronts: Reflection, Refraction, Diffraction — Advanced

Wavefront geometry provides a useful way of describing propagation.

Reflection changes direction while maintaining the wave in the same medium.

Refraction follows from different propagation speeds across a boundary.

Diffraction becomes increasingly noticeable when the size of an aperture or obstacle is not much larger than the wavelength.