Ultraviolet light
Ultraviolet light (UV) is regarded more as a range of
wavelengths rather than anything specific. It is present in natural sunlight.
However, it is invisible to the naked eye. The term ultraviolet derives from
the Latin word ultra meaning "beyond". Violet is the colour of the
shortest wavelengths of visible light and ultraviolet has an even shorter
wavelength that goes beyond this range. UV light from the sun is responsible
for tanning of the skin, but over exposure to this light can cause sunburn and
even some forms of skin cancer.