A band of colors called the <I>visible spectrum</I> forms when white light passes through a <I>prism</I> (a specially shaped glass object). The prism bends the shortest light waves most. They appear violet. It bends the longest waves least. They appear red. All other colors lie in between. Ultraviolet and infrared fall outside the spectrum and are invisible to people. The length of light waves is measured in <I>nanometers.</I> One nanometer is a billionth of a meter, or about 1/25,000,000 of an inch.
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World Book illustration by Leonard Morgan</P>
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