Thomas Caskin, age 11, of Lansing, Mich.., for his question:

What are ultraviolet rays?

Ordinary light is part of Electromagnetic Energy. Its wave lengths are just The right size for our eyes to see. The wave lengths of ultraviolet are a little Shorter than those of visible light. We cannot see them, but they reach us as part Of the Seething Electromagnetic Energy from the sun. These are the invisible Untraviolet rays which scorch our skins and give us our summer sun tans. Too much ultraviolet causes a dangerous burn. It kills many bacteria and other Small forms of life. For this reason, ultraviolet light is used to destroy germs In milk and other foods. An ultraviolet lamp may be used to destroy germs around an open wound and speed up the healing process.