What Is Ultraviolet Radiation? What Are Ultraviolet Radiations Used For?
Ultraviolet radiations are electromagnetic rays which are like light rays, but are not visible to the human eye. It is a part of the spectrum outside the visible range, just beyond the visible violet portion. UV radiation is present in sunlight, and constitutes about 10% of the total electromagnetic radiation output from the Sun.
The earth receives ultraviolet rays from the Sun. Too many ultraviolet can burn and kill. A layer of the Earth’s atmosphere, called the ozone layer, stops too many coming through. The few that do come through help to form vitamin D in the body and also cause sun tan.
Although long-wavelength ultraviolet is not considered an ionizing radiation because its photons lack the energy to ionize atoms, it can cause chemical reactions and make some substances glow or shine. This is called fluorescence. These rays can be used to look at tiny amounts of fluorescent material, too small to be seen otherwise.
Consequently, the chemical and biological effects of UV are greater than simple heating effects, and many practical applications of UV radiation derive from its interactions with organic molecules.
It is also produced by electric arcs and specialized lights, such as mercury-vapor lamps, tanning lamps, and black lights. UV radiation is widely used in industrial processes and in medical and dental practices for a variety of purposes, such as killing bacteria, creating fluorescent effects, curing inks and resins, phototherapy and sun tanning. Different UV wavelengths and intensities are used for different purposes.