Wave Behaviour

Reflection and Refraction

Reflection is the phenomena when a wave bounces back after hitting a boundary. The angle of incidence equals the angle of reflection.
Refraction is the bending or changing direction of a wave passing from one medium to another, often due to the change in wave speed.
The wave normal is the line perpendicular (at 90 degrees) to the barrier at the point of incidence during reflection and refraction.
Snell’s law defines the path of a refracted wave as n1sin(θ1) = n2sin(θ2).

Coherent waves originate from the same source and have a constant phase difference. They also have the same frequency.
Phase difference is measured in degrees (0° to 360°) or radians (0 to 2π). A phase difference of 180° or π radians is equivalent to being half a cycle in or out of phase.
This phase difference can be found by studying the wave’s displacement from equilibrium at specific points.

Two coherent waves can produce interference patterns. A wave interferes constructively with another when their phase difference is a multiple of 2π (including 0), resulting in an increased amplitude at the observed point.
Further, a wave interferes destructively with another when their phase difference is an odd multiple of π, resulting in an decrease or even cancellation of amplitude at the observed point.

Diffraction is the spreading of waves when they pass through a gap or around an obstacle.
Significant diffraction occurs when the gap or obstacle is approximately the same size as the wavelength of the waves.

The Doppler effect changes the observed frequency and wavelength of a wave due to the relative motion between the source of the wave and the observer.
If the source is moving closer, the observer perceives a higher frequency (shorter wavelength); if the source is moving away, the observer perceives a lower frequency (longer wavelength).