Waves and Wavefronts
Waves and wavefronts are distinct objects. A wavefront is made up of many different waves moving together. Each wave is perpendicular to the wavefront where it meets the wafront.
When a wave undergoes reflection, each wave obeys the law of reflection, with the angle of incidenceequal to the angle of reflection
The wavefronts also obey a law of reflection. First though, we have to draw the waves perpendicular to the wavefront. The angle of incidence for these waves will then equal the angle of rellection. We can construct the reflected wavefronts since these will be perpendicular to each wave.
The same principle can be applied to illustrate refraction of waves.