Huygens’ Principle
In 1678, a Dutch physicist, Christian Huygens, studied wave behavior and proposed that the wavefronts of light waves spreading out from a point source can be regarded as the overlapped crests of tiny secondary waves – that wavefronts are made up of tinier wavefronts.
Wavefronts are an array of identical waves that have the same source and travels through a homogeneous medium, thus their corresponding crests and troughs are in the same phase at any given time. These waves, then completed identical fractions of their cyclic motion. Therefore, an imaginary surface depicting parallel points of a wave that vibrates in accord is considered a wavefront.
Huygens’ Principle
“Every point of a wavefront may be considered the source of secondary wavelets that spread out in all directions with a speed equal to the speed of propagation of the waves.” …show more content…
Huygens’ Principle applied to a spherical wavefront.
The spherical wavefront in Figure 1 shows that a source emits a wave and that if all points along the wavefront AA’ are sources of new wavelengths, after a short period of time, the new overlapping wavelets would then form a new surface BB’, which can infer as the envelope of all the wavelengths.
As the waves spread, a segment appears less curved. As stated in Huygens’ Principle “The new wavefront is the tangential surface to all of these secondary wavelets.” And according to Huygens’ Principle, a plane light wave propagates though free space at the speed of