What’s UV Light?

UV, or ultraviolet, light is an invisible form of electromagnetic radiation that has a shorter wavelength than humans can see. It carries more energy than visible light and can sometimes break the bonds between atoms and molecules, altering the chemistry of the materials exposed to it. UV light can also cause some substances to emit visible light, a phenomenon known as fluorescence. This form of light, found in sunlight, can be beneficial to your health, as it stimulates vitamin D production and can kill harmful microorganisms, but too much exposure can cause sunburn and increase your risk of skin cancer. UV light has many uses, including disinfection, fluorescent light bulbs, and astronomy.

The term “ultraviolet” means “beyond purple”. In the visible part of the spectrum, the wavelength decreases – and the energy of the electromagnetic waves increases – from red to orange, yellow, green, blue and violet, so UV light has a shorter and more wavelength. violet light energy. Wavelengths are measured in nanometers (nm), or billionths of a meter, and ultraviolet wavelengths range from 10 nm to 400 nm. It can be classified as UV-A, UV-B or UV-C, in order of decreasing wavelength. An alternative classification, used in astronomy, is “near”, “medium”, “far” and “extreme”.

The Sun produces ultraviolet light of all categories; however, the shorter and higher wavelengths of energy are absorbed by oxygen in the atmosphere and, in particular, by the ozone layer. Consequently, the ultraviolet that reaches the surface consists mainly of UV-A, with some UV-VB. It is UV-B that is responsible for sunburn. Sunlight reaching the earth’s surface has both benefits and dangers.

Benefits

Ultraviolet light, especially UV-B, is needed for the skin to make vitamin D. It converts a chemical found in the skin into a vitamin precursor, which then forms the vitamin itself. This vitamin is essential for human health, and its deficiency has been implicated in immune system disorders, cardiovascular disease, high blood pressure, and various types of cancer. Severe deficiency causes the bone disease called rickets. Lack of sunlight is the main cause of vitamin D deficiency, and sunscreen prevents its formation.

There are other benefits associated with ultraviolet light that may appear to be independent of vitamin D production. Frequent exposure to moderate amounts of sunlight—that is, amounts not enough to cause sunburn—may provide some protection against skin cancer. There is evidence that people with outdoor occupations are less susceptible to the disease. Children who spend a lot of time outdoors also appear to be less at risk of developing skin cancers later in life. Other possible beneficial effects include reducing the incidence of cardiovascular disease, improving certain skin conditions, and improving mood.

Many potentially harmful microorganisms are quickly killed or inactivated by UV exposure. Airborne virus infections, such as the flu, are usually spread by droplets expelled by coughing and sneezing. The viral particles in these droplets don’t survive long when exposed to sunlight, and as a result, these diseases may not spread as easily in sunny conditions.
dangers

The ability of ultraviolet light to cause chemical changes also has its dangers. Stronger UV-B is responsible for sunburn, can cause premature skin aging, and can alter DNA in a way that can lead to skin cancers, such as melanoma. It can also damage the eyes and cause cataracts. UV light stimulates the production of the pigment melanin, and because of this, people may intentionally expose themselves to strong sunlight to get tanned skin. The effects associated with this form of light can be compounded by the popularity of tanning studios and tanning beds, which use artificially produced ultraviolet light to cause a tan.

it is used
Disinfection and sterilization

The effects of UV light on viruses, bacteria and parasites have led to its use in disinfecting drinking water supplies. It has the advantages of requiring little maintenance, of not altering the taste of the treated water and of not leaving potentially harmful chemicals. The main disadvantage is that, unlike some chemical methods, such as chlorination, it does not protect against contamination after treatment. UV is also used for food sterilization and in microbiology laboratories.
Fluorescence

Some substances, when exposed to UV light, emit light at visible wavelengths, a phenomenon known as fluorescence. Common fluorescent lamps, for example, are powered by UV light produced by the ionization of mercury vapor at low pressure. This light is absorbed by a special fluorescent coating, which in turn produces visible light. Fluorescent lights are more energy efficient than conventional light bulbs.

Ultraviolet light is often used in security. Sensitive documents, such as currency, driver’s licenses, credit cards and passports, have invisible symbols that only illuminate in the presence of UV light. These are difficult for counterfeiters to copy.
Biologists and zoologists are very fond of ultraviolet light as it helps them carry out nocturnal field surveys of organisms. Some birds, reptiles, and invertebrates, such as insects, fluoresce under UV light, and flashing a light rapidly over a small area can allow observers to count the approximate number of organisms of a given type. This is very useful because many of these animals are mainly nocturnal and rarely, if ever, seen during the day.
Many fabrics used in clothing are also fluorescent, and the “black lights” often used in nightclubs and parties exploit this fact by making clothes glow in the dark. These lights primarily produce light in the UV portion of the spectrum, but also produce a slight purple glow. Special posters or other artwork may also be created with the express purpose of fluorescing in a certain way under a black light.
insect traps
Many insects can see and are attracted to ultraviolet light, so light is often used in insect traps. These can be used by entomologists to study the insect population in a specific habitat or to trap and kill nuisance insects in restaurant food stores.
Astronomy
Mapping the Milky Way and other galaxies in ultraviolet light allows astronomers to create a picture of how galaxies evolve over time. Young stars produce more UV radiation than older stars, such as the Sun. They also produce a greater proportion of their ultraviolet light at the far end of the spectrum. Areas where new stars are forming therefore shine brightest in UV, allowing astronomers to identify and map these areas.
other uses
There are a number of other uses for UV light:
Spectrophotometry — for the analysis of chemical structures.
Analysis of minerals: Fluorescence under ultraviolet light can distinguish between minerals that look the same under visible light.
Microscopy: The shorter wavelength of ultraviolet light can resolve details too small to be seen with an ordinary light microscope.
Chemical markers: Substances that fluoresce under UV light, such as green fluorescent protein (GFP) can be used to study biological processes.
Photochemotherapy – this is used as a treatment for psoriasis and some other skin conditions.
Very fine resolution photolithography: It is used in the production of semiconductor components in the electronics industry.
Checking Electrical Insulation: “Coron discharge,” where damaged insulation of electrical equipment causes ionization of the air, can be detected by the emission of ultraviolet light.
Curing of Adhesives and Coatings: Some substances cure and harden on exposure to ultraviolet light.

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