Diffraction (Encyclopedia of Science)
Diffraction is the bending of waves (such as light waves or sound waves) as they pass around an obstacle or through an opening. Anyone who has watched ocean waves entering a bay or harbor has probably witnessed diffraction. As the waves strike the first point of land, they change direction. Instead of moving into the bay or harbor parallel to (in the same direction as) land, they travel at an angle to it. The narrower the opening, the more dramatic the effect. As waves enter a narrow harbor opening, such as San Francisco's Golden Gate, they change from a parallel set of wave fronts to a fan-shaped pattern.
The diffraction of light has many important applications. For example, a device known as the diffraction grating is used to break white light apart into its colored components. Patterns produced by diffraction gratings provide information about the kind of light that falls on them.
All waves are subject to diffraction when they encounter an obstacle in their path. Consider the shadow of a flagpole cast by the Sun on the ground. From a distance the darkened zone of the shadow gives the
(The entire section is 1048 words.)
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