Ultraviolet light (UV) is a part of normal electromagnetic radiation.
But it cannot be seen with naked eyes unlike visible light.
UV is light energy with the wavelengths in the range of 10 to 400nm.
It is present in sunlight and can also be produced by electric arc lamps.
It has a higher frequency and shorter wavelength than visible light.
This means this radiation has greater energy than normal visible light.
It can cause chemical reactions and make other substances to a florescence.
Hence UV light is a bit harsh on the skin and eyes when directly exposed.
The ozone layer on the surface of the earth prevents them from reaching the earth to a large extent. This saves us from the harmful effect of UV light from the sun.
But Ultraviolet light has been found to have many applications to man.
Ultraviolet Light Uses
1. Analytical research
2. Medicine as photo-therapy
3. Vitamin D formation and strengthen bones
4. Sterilization of substances
5. Air purification
6. To trap insects
Analytical research: UV light is widely used in the analysis of substances. The spectrophotometers employ UV light to detect and measure the concentration of a given sample in liquid form. These spectrometers are used individually or in combination with other techniques like chromatography.
Besides these certain plant extracts and chemicals are stained or have inherent dyes that make them detectable when kept in the UV environment. For this, the sample is put in a UV chamber and observed.
Thus UV light helps in the analysis and research of many chemical and biological substances.
In Medicine: For certain skin diseases like psoriasis and other skin conditions, the prolonged exposure to UV light is better therapy.
The exposure to UV light is called as photo-therapy. Here the patient will be relieved of the problems even without the use of medicines but just by exposure to the light.
Even newborn babies can have jaundice due to the break down of hemoglobin. Then doctors treat them by phototherapy by using bright light or UV light.
When the skin of a baby is exposed to light for long periods, the bilirubin in the skin breaks down to water-soluble form and gets out of the body through urine.
Vitamin D formation: Vitamin D is a type of vitamin that needs not to be consumed from food. It is synthesized in the skin due to the irradiation of ergosterol by sunlight. UV light in the sun is key for the formation of Vitamin D. Thus the formed Vitamin-D helps the storage of calcium in the bones and thereby strengthen them.
Sterilization of substances: UV radiation is a type of dry heat method of sterilization. For details go through sterilization methods. UV when falls on the cells, it can destroy the DNA and other essential molecules due to its energy. Hence when the substances are exposed to UV light at predefined wavelength and time, there will be effective sterilization.
This method of sterilization can be used for bulk process and also for keeping a specific room or chamber sterile.
You would have notice presence of UV ray screen on the door entrances in hospitals and other sterile areas. This UV stream kills microbes present on human surfaces while entering the concerned rooms.
Air purification: Air is composed of organic debris, carbon monoxide, and even some microbes.
This air can be purified by UV radiation.
UV radiation has enough energy to kill the microbes and also destroys the organic debris and carbon monoxide.
So employing a UV light source can help purify the air around.
To trap insects: Insect trap instruments have UV light emitters.
This UV light produces enough heat to attract insects and trap them.
Thus these instruments can keep insects away from us.
In 1945 my parents had a floor lamp that had a ultra violet bulb and a timer and you wore sunglasses. I can not remember what it was used for. My parent used it on my sister and me. Would any one like to guess?
Could they be used on cruise ships on incoming bags to stop viruses from entering the ships? What about airport baggage also? I saw a unit being used down the aisle of an airliner to cleanse the inside of the plane instead of spraying.
Thanks for asking eh ! Eric Bertram
Hi Eric, for closed baggage sterilization, I think ionizing radiation would be effective UV radiation.
Thank You for the refresher of information in microbiology and ultraviolet.