What is Ultraviolet Radiation? - Definition, Uses & Effects

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  • 0:00 What Is Ultraviolet Radiation?
  • 0:45 Effects
  • 1:35 Uses
  • 2:15 Lesson Summary
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Lesson Transcript
Instructor: David Wood

David has taught Honors Physics, AP Physics, IB Physics and general science courses. He has a Masters in Education, and a Bachelors in Physics.

In this lesson you will learn what ultraviolet radiation is, how it is used, and its effects on humans, both positive and negative. A short quiz will follow.

What is Ultraviolet Radiation?

Our eyes can see a lot, but they can't see everything. The light our eyes can see is made up of electromagnetic radiation, but there's a lot more our eyes can't see. Beyond the red end of the spectrum there is infrared radiation, microwaves and radio waves, and beyond the violet there is ultraviolet, x-rays and gamma rays. The full electromagnetic spectrum is shown in the following image:

The Electromagnetic Spectrum
The Electromagnetic Spectrum

Ultraviolet literally means beyond violet in Latin, because it is nothing more than electromagnetic radiation just beyond what our eyes can see on the violet side of the rainbow. The sun is our main source of ultraviolet, though the more dangerous wavelengths of ultraviolet are absorbed by the atmosphere, particularly the Ozone Layer.


Ultraviolet radiation has both positive and negative effects on the human body. Some ultraviolet is useful and necessary, because it allows our bodies to produce vitamin D. Although we can consume vitamin D, or take supplements, it is hard for our bodies to absorb orally. Getting plenty of sunlight is therefore important for good health.

But one can have too much of a good thing. Ultraviolet is also responsible for tanning and sunburn, two things that cause us to develop skin cancer.

Both these effects of ultraviolet derive from its ability to heat materials, and cause chemical reactions in them. While ultraviolet isn't high energy enough to ionize atoms, chemical reactions are enough to cause significant damage to human tissue. It can cause direct DNA damage, which leads to cancer, and it always damages collagen and vitamin A, causing skin-aging effects.


Ultraviolet has many practical uses. It can be used to confirm the validity of banknotes and identity cards. Messages or symbols can be written in fluorescent dye that can be viewed under a UV light.

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