Ultraviolet rays have a wavelength shorter than visible light rays, so humans can't see ultraviolet light although some animals, such as bees, are capable of seeing it. Ultraviolet rays can damage cells, so a beach visitor may put suntan cream on her skin to protect it from ultraviolet light. Ultraviolet rays are useful to humans for sterilisation and scientific measurement.
A hospital can take advantage of the destructive quality of ultraviolet light by shining it on counter tops, surgical tools and other items in order to sterilise them. A medical device manufacturer can also use ultraviolet light to remove harmful bacteria from medical implants. Ultraviolet rays don't leave any residue behind, which makes cleanup easy.
Ultraviolet rays can treat certain diseases. During ultraviolet therapy, the ultraviolet rays kill fungus infections and can remove skin rashes and discolouration, according to the Baylor College of Medicine. Shining ultraviolet light directly on the skin as a medical treatment is risky because ultraviolet light can also cause skin cancer.
Water treatment facilities also shine ultraviolet rays on water to remove harmful organisms. According to West Virginia University, ultraviolet light treatment is useful if a chemical spill occurs because it can destroy toxic chemicals before they contaminate local waterways. Ultraviolet water purification does not leave any aftertaste behind.
Spectroscopy uses ultraviolet rays to identify chemicals. Some chemicals do not absorb much visible light, but they do absorb ultraviolet rays well. According to Michigan State University, ultraviolet light helps scientists identify double and triple carbon bonds, so it can help determine the molecules in a blend of gasoline.
Ultraviolet light is useful for manipulating and viewing very small objects. An ultraviolet microscope uses ultraviolet rays to help a scientist see objects that are too small to view with visible light. Ultraviolet rays are also useful for high-tech manufacturing. A computer chip fabricator, for instance, can use ultraviolet rays to etch designs on the chips.
Ultraviolet rays provide images of very distant objects. According to the National Aeronautics and Space Administration (NASA), an ultraviolet telescope provides a better view of the younger stars in a galaxy because older stars produce more red and yellow light, so it is difficult to see the newer stars with a standard telescope.