The Effect of a Narrower Opening

A narrower opening results in more nearly circular waves.

Discussion

Here the opening in the barrier is about the same size as the wavelength at the beginning of the movie, and that part of the wave that passes through the opening is diffracted into a more nearly circular form than in the previous movie. The wave pattern at the beginning of this movie resembles that of waves generated by a point source. As the wave frequency is increased and the wavelength decreases, the extent of diffraction is reduced, becoming negligible at very high frequencies. This effect is best seen by comparing images from the beginning and middle of the movie with those near the end.