While it can’t be seen by the naked eye, ultraviolet light influences many parts of our daily lives. Recognition for the breakthrough of ultraviolet light is given to Johann Wilhelm Ritter. Ritter was born in Samitz, Silesia in 1776 and attended the University of Jena studying medicine and science. In 1800 William Herschel discovered infrared light, this showed that there was a form of light beyond what is visible to the human eye. After hearing about this discovery, Ritter was motivated to do some trials of his own. Herschel discovered light beyond the red end of the spectrum, so Ritter wondered if there was non-visible light beyond the violet end of the spectrum. One year later in 1801, he discovered ultraviolet light.
His discovery originated by experimenting with silver chloride. Silver chloride is a chemical that turns dark when it is showed sunlight. Just like Herschel, Ritter fixed sunlight through a glass prism, creating the light spectrum. Ritter placed the silver chloride next to the violet end of the light spectrum and the silver chloride turned black, even though no visible sunlight was shining on it. This demonstrated that there was a form of light outside the violet end of the spectrum as well. At first, Ritter denoted this light as “Chemical Rays” but later it was referred to as ultraviolet light – meaning ‘light beyond violet’ in its literal sense. This discovery showed that there was in fact light existing beyond either end of the visible spectrum.
Ultraviolet light is a form of electromagnetic radiation – it stems from the sun and is transmitted in waves; these patterns of waves are also referred to as the electromagnetic spectrum. This spectrum is comprised of radio waves, microwaves, infrared light, visible light, ultraviolet light, x-rays, and gamma rays. Ultraviolet falls in-between x-rays and visible light with a frequency of 8 × 1014 to 3 × 1016 cycles per second and a wavelength ranging from 380 to 10 nanometers. Ultraviolet light is commonly divided into three sub-groups based on the length of its wavelength. UV light with a wavelength of between 315-400 nm is considered UVA or ‘near UV’, a wavelength of 280-315 nm is known as UVB or ‘middle UV’ and wavelengths of 180-280 nm are referred to as UVC or ‘far UV’. Ultraviolet light with wavelengths of 10-180 nm are not included in these subcategories because they are blocked by air and can’t get past the ozone layer, but they can be referred to as extreme UV.
The most amount of ultraviolet light that people meet in their normal day is from the sun. When we walk outside in the day time, UV light is diffused from the sun to our skin. This is what gives us the ability to produce vitamin D, which is an essential vitamin humans need. However, too much exposure to UV waves transmitted from the sun can become very dangerous very quickly. Ultraviolet light has a higher frequency than visible light, because of this – UV light has more energy and can enter our skin. In effect, too much contact to UV rays can damage your DNA.
UVB, also referred to as Middle UV, is the most dangerous type of ultraviolet radiation. This is the form of UV that can’t be absorbed by the atmosphere, so it can have the detrimental effect of damaging your cellular DNA. Being bare to these waves for too long is what causes sunburns, skin blisters, and even the progress of skin cancer. Even though there is a huge risk associated with exposing your skin to this type of radiation, there is no way around avoiding it. It can also be beneficial to us in many ways including helping us produce Vitamin D, which is crucial for your body to absorb calcium and promote bone growth as well as helping fight off diseases.
UVA, also referred to as near UV, is the type of ultraviolet light that is most commonly met. This is also the least harmful type of UV wave. UVA causes your skin to progressively tan, but could also lead to sunburn when exposed for a long period of time. Even when it is cloudy outside, UVA rays still pierce through the clouds and can absorb in your skin. This wavelength also plays a role in the crucial development of vitamin D. But UVA also has negatives, just like UVB. When overexposed to UVA rays, your skin can burn, wrinkle and you can even develop skin cancer.
These rays can also be produced through other things like UV lamps. These lamps are what is used in tanning beds. The use of these can give people accelerated tans, but it is a very controversial use of UV light. There are many studies showing how dangerous too much exposure to UV light can be for your skin, and the long-term effects – leading people to become very skeptical to exposing their bodies to such direct UV radiation for such a long period of time. Many doctors and dermatologists highly recommend not using these tanning beds, especially if you are under 30 years old because it has a high chance of forming into an early development of skin cancer.
While there are benefits and necessities to exposing yourself to UV rays, there are also protective measures you can take when you think you will be exposed to them for too long. People that are unprotected to UV rays for long periods of time are more prone to developing skin cancer, so it is important to know the options for preventing this. The most common preventive is wearing sunscreen. Sunscreen contains minerals like zinc or titanium dioxide which reflect UV rays away from our skin. However, sunscreen cannot block all UV rays, but it can help protect your skin when you are exposed to UV rays for a long amount of time. Wearing long shirts and pants can also limit your exposure to these rays but it is also not 100% effective. One way to make sure you are being as effective as possible is to make sure you can’t see through the clothes you are wearing. If you can see through them then that means the ultraviolet rays can get through them as well. Another way you can protect yourself from UV rays is by wearing UV-blocking sunglasses. Just like your skin, the UV rays can penetrate your eyes and can put you at risk for developing eye diseases. So, by wearing UV protecting sunglasses, you can have an additional protective measure.
UV light isn’t just used for giving us glowing tans in the summertime, it is also used in the medical field. UV light can also be used for sterilization and disinfestation. Hospitals can utilize UV lamps for sterilize surgical gear – this is a good alternative for objects that could be impaired by heat sterilization. Not only that, but UV lamps can also sterilize and disinfect the air in the room – also making it a good option to have in operating rooms as well as patient rooms to stop germs from spreading. It neutralizes DNA from pathogens, making it impossible to reproduce. Not only is UV light useful for sterilizing equipment in the medical field, but used with other therapies, UV light can treat persistent diseases. In some instances, it can be used as cancer treatment. While it might not make sense why UV light could cause but also treat cancer, UV light can majorly slow down the growth of the disease, which plays a huge part in the overall development of the disease.
Another field where ultraviolet light can play a huge part is in Forensics. UV light can recognize body fluids by becoming fluorescent when UV light is shined onto it. This can be utilized in many different crime scene scenarios where blood or other fluids could be unseen by the naked eye. UV light can also be used in forensics when determining if certain art paintings are originals, or analyzing if signatures are legit. You can also use ultraviolet light when verifying currency. By using a UV light and shining it on a U.S. bill, you can analyze the embedded strips that show only under UV light. This is an easy and efficient way of determining whether a U.S. bill is authentic or not.
In another aspect, UV light is useful in astronomy when discovering new objects in space. In space, there are objects and galaxies that can be seen in visible light, but on the other hand, there are galaxies that can only be seen in ultraviolet light. Most objects in the sky are relatively cool in temperature, however, ultraviolet light helps us find hotter temperature objects in space. These objects are normally either in their very early or their very late stage of development. This is very interesting and useful information because it shows us when a new object in the universe is been created, and when a current object in our universe are about to be destroyed.
All the examples above show that there are many uses for ultraviolet light, and it plays a huge part in our lives. While we might not think about it very often, we are exposed to it almost every day and learning more about its uses and its dangers is important. While it’s good to know all the benefits to UV light, it is also important to know how dangerous it can be. If not handled properly UV rays can give off large amounts of radiation that would do much more harm than good for your body. Thanks to Herschel, Ritter was inspired into discovering ultraviolet light which has forever changed how we see and experience our world.
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