6.3 Huygens' principle

6.3 Huygens' principle (ESBNG)

Christiaan Huygens described how to determine the path of waves through a medium.

The Huygens' Principle

Every point of a wave front serves as a point source of spherical, secondary waves. After a time t, the new position of the wave front will be that of a surface tangent to the secondary waves.

Huygens' principle applies to any wavefront, even those that are curved as you would get from a single point source. A simple example of the Huygens' Principle is to consider the single wavefront in Figure 6.2.

Worked example 1: Application of the Huygens' principle

Given the wavefront,

use the Huygens' Principle to determine the wavefront at a later time.

Draw circles at various points along the given wavefront

Join the circle crests to get the wavefront at a later time