What is UV Radiation? - Definition, Types & Effects

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  • 0:00 UV Radiation
  • 0:31 Wavelength, Frequency & Energy
  • 1:50 Types & Effects
  • 3:02 Preventative Measures
  • 3:36 Lesson Summary
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Lesson Transcript
Instructor: Nicola McDougal

Nicky has taught a variety of chemistry courses at college level. Nicky has a PhD in Physical Chemistry.

It's summertime, and you're applying sunscreen to avoid sunburn. But did you wonder what sunscreen does and what it protects us from? In this lesson, we'll learn all about UV radiation and some of its effects.

UV Radiation

Ultraviolet (UV) radiation is defined as that portion of the electromagnetic spectrum between X-rays and visible light or between 40 and 400 nanometer (nm) wavelengths. The primary source of UV radiation is the sun. There are also a number of artificial sources, such as tanning booths and halogen lights. The different sources come with some unique hazards, depending on the wavelength range of the emitted UV radiation.

Wavelength, Frequency & Energy

Before we can think more about UV radiation and its effects, it is important to revisit two very important properties of waves: wavelength and frequency.

Wavelength is the distance between two successive peaks (or troughs). Frequency is the number of waves passing a fixed point in one second. Wavelength and frequency are related by this relationship: frequency x wavelength = speed of light. The speed of light is the fastest any wave can travel, or 3.0 x 10^8 m/s. Therefore, as a wavelength gets longer, frequency must decrease to maintain this relationship. This is called an inverse relationship.

We can imagine electromagnetic radiation as a wave of light that carries energy through space. Different wavelengths of light carry different amounts of energy. In general, the longer the wavelength, the lower the energy associated with that wave. Long wavelengths also have low frequency. When you look at the electromagnetic spectrum, you'll see the wave with the highest energy is gamma radiation; it has the shortest wavelength. The lowest energy waves are radio waves. Ultraviolet radiation has a relatively short wavelength and so has relatively high energy.

Types & Effects

The three most common types of UV light are UV-A, UV-B and UV-C, as shown in this table.

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