Wave Diffraction by an Opening in a Barrier

When linear waves pass through an opening whose width is comparable to the wavelength of the wave, approximately circular waves are generated.

Discussion

An opening in a barrier will act as a point source for waves passing through it if the width of the opening is about the same size or smaller than the wavelength. Here waves encounter a barrier with an opening that is larger than the wavelength. The part of the wave that passes through the opening is diffracted only near the edges. As the wave frequency is increased and the wavelength decreases, the extent of diffraction is reduced. It essentially vanishes at high frequencies. This effect is best seen by comparing images from the beginning and middle of the movie with those near the end.