Diffraction page 119

Have you ever wondered

why you can hear noises coming

from around corners? Or how  lighting 

shining through a tiny hole can illumination the entries room? The reason is a process which is called diffraction. Diffraction occurs when a sound or light wave passes through a gap that is smaller than its wavelength. The wave does not stop but travels on to the other side with the same frequency and wavelength. The only diffraction is that the wave now side with ripple out in all direction. It's as if the gap has made the wave start again from a single point.