What Is Ultraviolet Light? Everything You Need to Know

UV light from repair set and welding tool

What Is Ultraviolet Light? Everything You Need to Know

After a long day in the sun, you may come back with burning sensations and red skin. A trip to the beach is typically associated with sunscreen or sunburn. However, it might have more to do with it than you think. From tanning booths to cancer treatment, ultraviolet light plays an integral role in our lives. If you’re getting flashbacks to your grade school science class, don’t fret. Continue reading for everything you need to know about ultraviolet radiation and how it affects you.

What is Ultraviolet Light?: Complete Explanation

Ultraviolet (UV) light is a type of electromagnetic radiation that sits just above the spectrum of light that we can see with unaided eyes. It makes up a portion of the electromagnetic spectrum, with its wave frequencies measuring less than X-rays and blending into the violet range of visible light.

The electromagnetic spectrum is typically measured in three metrics, depending on which is easiest to read. These include wavelength, frequency, and energy. Ultraviolet is typically measured in wavelength (meters) or frequency (hertz). While there’s no hard line to define the boundaries of UV, it typically ranges from 180 to 400 nanometers (nm).

Ultraviolet light has a unique energy that causes them to break chemical bonds. This results in a variety of benefits, such as purifying water systems. However, overexposure can lead to damaging consequences such as sunburn.

This portion of the electromagnetic spectrum comes from various natural and artificial sources. Its prevalence in new stars allows scientists to explore the universe as it formed. Furthermore, humans have used UV in practical applications following its discovery in the 1800s.

Ultraviolet Light: An Exact Definition

The U.S. Navy defines ultraviolet light as “part of the electromagnetic radiation spectrum,” where “electromagnetic radiation is made up of oscillating electric and magnetic fields which are propagated in free space and matter.” The military agency defines its wavelengths, which range “from approximately 180 nanometers (nm) to 400 nanometers.”

The ultraviolet spectrum varies based on its physiologic effects. The Navy breaks down UV radiation into critical ranges:

  1. UVA (near UV) 315 – 400nm
  2. UVB (middle UV) 280 – 315nm
  3. UVC (far UV) 180 – 280nm

Where Does Ultraviolet Light Come From?

The Sun

sun shining over the ocean
The sun produces all three ranges of UV.

Our sun is the largest producer of ultraviolet radiation within the range of our influence. Far UV is the most dangerous, but the atmosphere absorbs nearly all its wavelengths. It also absorbs about 95% of middle UV, which is the cause of sunburn. This is why it’s okay to be in the sun while not overexposing yourself.

Young Stars

In astronomy, scientists use the electromagnetic spectrum to evaluate the age and characteristics of star clusters. NASA researchers have discovered that ultraviolet images of galaxies reveal star nurseries, with young stars producing energy much more powerful than our own sun. Evaluating the universe in the ultraviolet allows us to discover how stars form. 

Electric Arcs

In addition to the ultraviolet light from celestial bodies, energy waves of this type have been found in electric discharges. This occurs during the breakdown of gas and finds use in specialized lamps.  

How Do You Create Ultraviolet Light?

One way to artificially produce ultraviolet light is with an electric discharge passing through a gas. Mercury vapor is the most used option in practical applications due to its consistency. The mercury vapor absorbs the UV radiation from the electric discharge and emits visible light as an exhaust. 

Who Discovered Ultraviolet Light?

Ultraviolet rays were discovered in 1801 by German chemist Johann Wilhelm Ritter while searching for the polarities in the forces of nature. While experimenting in the opposite direction of William Herschel’s “heat rays,” Ritter discovered that silver chloride paper reacted to invisible frequencies faster than it did to violet. 

This experiment proved the existence of wavelengths beyond the visible light spectrum, with Ritter naming the wavelength deoxidizing rays for their ability to alter the chemical balance of objects. The name was dropped near the end of the century in favor of the more accurately descriptive name ultraviolet.

What Are the Applications of Ultraviolet Light?


While too much exposure to ultraviolet can lead to sunburn, people often use the frequency in moderation to tan skin. Tanning is most effective when subjected to UV wavelengths of 280 – 315nm. This can occur naturally through sun exposure or artificially with tanning lights.


white long fluorescent light tube
Fluorescence tube is a low-pressure, mercury-vapor gas-discharge lamp.

When specific objects are exposed to ultraviolet radiation, they can absorb it. UV waves that are absorbed cause the electrons within the object to increase in energy. As the electrons return to their original energy level, they emit the energy as absorbed light. This phenomenon, called fluorescence, results in some objects glowing or appearing brighter. We often see fluorescence used in safety equipment, where visibility is critical.

Vitamin D 

In addition to its effects on the skin, UVB causes the body to produce vitamin D. This vitamin helps create serotonin, which is associated with sensations of happiness and joy. The World Health Organization recommends 5-15 minutes of direct sunlight on the skin for high vitamin D levels.

Applications of Ultraviolet Light In the Real World

Psoralen Ultraviolet Light Treatment

Cancer Research UK is a nonprofit organization that’s exploring the use of ultraviolet light to treat skin conditions. Physicians use specific medicinal applications to increase the sensitivity of their patient’s skin. A UV light is directed at the condition, which slows down the growth of problem cells. Psoralen ultraviolet light treatment (PUVA) is used to treat lymphoma, psoriasis, and eczema, among other conditions.

Aurora Borealis

Similar to how some objects glow fluorescent light when exposed to UV radiation, so do the atmospheric gases at the earth’s magnetic poles. The Aurora Borealis (also known as the Northern Lights) occur around the Arctic and Antarctic when ultraviolet radiation concentrates in those magnetic fields. The radiation bounces off gas particles (usually oxygen atoms), which get excited and raise energy. As the particles return to their natural level, they emit brilliant green (and sometimes red or blue) light. 

Hubble Space Telescope


The Hubble Space Telescope was launched into low Earth orbit in 1990 and remains in operation.

As part of the Great Observatories project in the 1990s, NASA launched the Hubble Space Telescope to observe the universe in visible and ultraviolet light spectrums. Equipped with cameras, spectrographs, and interferometers, the space observatory analyzes the beginnings of the universe. The Hubble Space Telescope focuses on distant points of light to explore how stars form.

Ultraviolet Light: Further Reading

With technology rapidly improving, it’s important to know how electromagnetic radiation like ultraviolet light applies. Both naturally and artificially occurring, UV positively and negatively affects us alongside the rest of the spectrum. To learn more about electromagnetic uses, check out the articles below.

Frequently Asked Questions

How does ultraviolet light compare to infrared?

Ultraviolet light and infrared are both portions of the electromagnetic spectrum. Ultraviolet radiation follows the violet wavelength of the visible light spectrum and has a higher energy value than infrared.

What is ultraviolet light in simple terms?

Ultraviolet light is a form of electromagnetic radiation, which are waves of energy that are more powerful than visible light waves and less powerful than X-rays.

What is ultraviolet light used for?

Ultraviolet light is commonly used in tanning beds or fluorescent lighting. However, some applications allow it to help cure skin conditions.

Why is it called ultraviolet light?

Ultraviolet is Latin for “beyond violet.” The wavelength receives this name for its location on the electromagnetic spectrum, as it follows the violet wavelength of visible light.

What is the electromagnetic spectrum?

The electromagnetic spectrum is the entire range of light waves that emit from objects. These vary in size depending on their frequency, wavelength, and energy.

What are the 7 electromagnetic spectrums?

The 7 portions of the electromagnetic spectrum are radio waves, microwaves, infrared light, visible light, ultraviolet radiation, x-rays, and gamma rays.

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