Ultraviolet rays or UV rays are electromagnetic radiations that lie within the frequency range of 800 terahertz and 30,000 terahertz. The wavelength range of ultraviolet waves is from 10 nm to 400 nm. In the electromagnetic spectrum, ultraviolet rays are present in between visible light and x-rays. Ultraviolet rays are invisible to the human eye; however, there are certain insects in nature who can see these radiations. UV rays were discovered by Johann Ritter, a German chemist, physicist, and philosopher, in 1801.
Examples of Ultraviolet Waves
Ultraviolet radiations are capable of killing bacteria and viruses. It has been experimentally verified that bacteria and viruses become inactive after being exposed to ultraviolet radiations. This property of the UV radiations is utilized in disinfecting the air, water, surfaces, and objects.
2. Water Purification
Water purifiers make use of ultraviolet radiations to refrain the bacteria, viruses, and other unwanted microorganisms present in the water to grow and multiply, thereby killing the germs and making the contaminated water fit for consumption. Purification of water with the help of ultraviolet radiation is one of the most reliable methods used in cleansing water.
3. UV Lamps
UV lamps are one of the most commonly used appliances in homes, hospitals, and offices. The lamp tube of a UV lamp consists of a small amount of mercury. When the electric current runs through the internal circuitry of the lamp, mercury gets excited and emits ultraviolet radiation. These ultraviolet radiations can be further used to perform multiple tasks such as disinfection, sterilization, illumination, etc.
4. Production of Vitamin D
Ultraviolet radiations help our body synthesize vitamin D. When our body is exposed to UV waves, the cholesterol present in our skin releases energy and gets converted into vitamin D. One of the prime sources of UV radiation is the sunlight, which is why doctors recommend a healthy exposure to sunlight to overcome the vitamin D deficiency.
One of the prime applications of ultraviolet radiation lies in the medicine industry. Hospitals make use of UV light for proper sterilization of the surgical instruments before the surgery. It is also used to sanitize or purify the air in the operation theatre or in other critical medical places where proper sterilization is a major concern.
6. Cure Skin Disorders
Ultraviolet radiations are used in the treatment of several skin disorders. These radiations are very helpful in reducing the inflammation of swollen muscles. UV rays also reduce the rate at which the skin cells get produced, thereby delaying the ageing process; however, prolonged exposure to the UV rays may lead to adverse side effects such as wrinkles, sunburns, skin cancer, etc.
Artificial tanning is very popular amongst the population with light-toned skin. The ultraviolet radiation present in the sunlight causes the skin cells to produce melanin. Melanin is the pigment responsible for tanning. To simplify and fasten the process of tanning, artificial UV tanning beds are used.
A number of celestial objects emit ultraviolet radiations. The rate of emission of the UV rays is proportional to the temperature of the celestial body. This means that the hotter the object, the more will be the emission of radiations. Hence, ultraviolet rays can be used to study the composition and characteristics of the planets, stars, and asteroids.
9. Fluorescence and Lightning
When ultraviolet radiations strike the surface of certain materials, it causes them to emit electromagnetic waves of comparatively low energy. This process of absorption of UV rays and emission of visible light is known as fluorescence. The fluorescence is commonly used for decoration purposes. The effect of ultraviolet radiations can be easily observed in highlighters. The fluorescent ink of the highlighters glows strongly when exposed to sunlight or ultraviolet radiations.
Curing is a chemical process that helps to add strength to a polymer by cross-linking its polymer chains. It is most commonly used in the food and the chemical industries to preserve food and chemical substances. UV curing is the process in which the toughening of the polymers is achieved with the help of ultraviolet radiations. UV curing can be used to trigger a photochemical reaction that can be used in screen printing.