Light Emission as Electromagnetic Waves
In the theory of light emission as electromagnetic waves, light is a type of electromagnetic energy. Electromagnetic waves with wavelengths of 380-780 nm that are visible to the eye are called visible light, which is a combination of different wavelengths.
The figure below shows the spectrum of electromagnetic waves and different colors:
Infrared waves fall within the range of 780-1000 nm. Infrared radiation is not visible to the eye and when it hits an object, it is absorbed and converted into heat. Infrared is the main factor in the transfer of heat from the sun to the earth.
The Nature of Light
UV-A spectrum causes tanning and is in the range of 315-380 nm.
UV-B spectrum causes skin redness and inflammation, sunburn, and is in the range of 280-315 nm.
UV-C spectrum is in the range of 100-280 nm and causes the destruction of cellular structures, thus it is used in purification and disinfection with radiation.
Unlike the positive effects of ultraviolet radiation (e.g., UV-B spectrum causes Vitamin D production in the body), an excessive amount of this radiation can be dangerous for the body.
The ozone layer absorbs a large amount of the sun’s ultraviolet radiation, especially the UV-C spectrum.
