ocr: JLIRAVIOLET RADIATION Electromagnetic radiation with a shorter wavelength (100 to 4000 A) than visible light. Ultraviolet radiation is produced by stars and, naturally, also by the Sun, which is our UV source. Ultraviolet light is divided into three groups: UV-A, UV-B and UV-C. The one with the lon- gest wavelength, UV-A, reaches all the way to the Earth's surface. Other wavelengths are UV radiation has harmful effects on usually halted by the ozone layer. humans, such as cancer and even ge- netic change. Powertul UV rays destroy One nm (nanometre) equals 10 A cells. This is why life could not ...
