According to Huygens’s principle, every point on a wavefront is a source of wavelets that spread out in the forward direction at the same speed as the wave itself. The new wavefront is tangent to all of the wavelets. A mirror reflects an incoming wave at an angle equal to the incident angle, verifying the law of reflection. The law of refraction can be explained by applying Huygens’s principle to a wavefront passing from one medium to another. The bending of a wave around the edges of an opening or an obstacle is called diffraction.