"Every point on a wavefront is in itself the source of spherical wavelets which expand out in the forward direction at the speed of light," according to Huygen's Principle.
The wavefront is made up of all of these spherical wavelets.
Huygen's principle states that all wavefront points will develop into secondary sources. The wavefronts will move as a result.
Each and every secondary source emits wavelets. The waveform's new position is at the tangent traced to each wavelet.
The following figure illustrates Huygen's Principle:
Applications of Huygen's Principle:
Huygens' theory applies to all sorts of waves, including water, sound, and light waves.
It is helpful not only for describing the propagation of light waves but also for understanding the rules of reflection and refraction.