Shandale Vassallo, age 8, of South Portland, Me., for her question:

IS WHITE A COLOR?

Light travels in waves. A narrow beam of white light spreads out into a beautiful band of colors when it passes through a transparent prism.

By using a prism to form the spectrum, we learn that white light is a mixture of many colored lights. Thus we can make colored lights from white light, and we can also make white light by mixing colored lights.

'We can recombine the colors of the spectrum to form white light if we put a second prism close to the first one and use it to "collect" the colors.

White is also called a color at one extreme end of the scale of grays, opposite to black.