Diffraction
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Diffraction is the process by which waves spread out and curve when they pass through a gap or pass around an object.
The amount of diffraction that occurs is dependent on the wavelength of the wave and the size of the gap. The closer the size of the gap is to the wavelength, the more diffraction occurs and the more curved the produced wave will be.
For example: a sound wave will diffract more through a large gap than a light wave.
If a slit is small enough relative to the wavelength, it will appear to be a point source, with a full 180o radiation pattern of equal magnitude.
If two such slits are placed close together, a characteristic interference pattern is observed; this is the classic experiment that shows the wave aspect of the nature of light.
