Paul S, Year 12
“In 1678, Huygens proposed that every point which a luminous disturbance reaches becomes a source of a spherical wave; the sum of these secondary waves determines the form of the wave at any subsequent time.” – Wikipedia
These Secondary waves are otherwise known as wavelets and have the same frequency and wavelength as the wave they come from.
This principle can be used to explain the propagation of light in different circumstances.
