Huygens principle states that:
Every point on a wavefront is in itself the source of spherical wavelets which spread out in the forward direction at the speed of light. The sum of these spherical wavelets forms the wavefront.
Huygens principle was proposed by Christiaan Huygens in 1678. It revolutionized our knowledge of light and its characteristics. This principle additional highlights things such as;
- Secondary sources start making their own wavelets, these waves are similar to of primary source.
- At any instant of time, a common tangent on the wavelets in the forward direction gives the new wavefront.
- The sum of spherical wavelets forms the wavefront.
Examples of Huygen’s Principle
If a stone is thrown into the river it will create waves around that point.
These waves look like circular rings and are called wavefront waves.
Gradually, the wavefronts disperse in all directions.