Electromagnetic Waves: Definition, Sources, Properties & Regions

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  • 0:01 What is an…
  • 1:21 Sources
  • 2:36 Regions of Waves
  • 5:08 Lesson Summary
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Lesson Transcript
Instructor: Kevin Newton

Kevin has edited encyclopedias, taught middle and high school history, and has a master's degree in Islamic law.

Electromagnetic waves power everything from your computer's Internet connection to your radio to atomic weapons. In this lesson, we'll look at the entire spectrum, as well as how they are formed and characteristics of each group of waves.

What Is an Electromagnetic Wave?

Have you ever cooked something in a microwave? Or, maybe you've turned up a speaker so loud that you could feel it? In either event, you are feeling the energy transferred by electromagnetic waves. An electromagnetic wave transfers energy through space along a regular pattern. It is called an electromagnetic wave because it is caused when electrons vibrate but cause vibrations of electric and magnetic forces on two different planes. However, what makes them really unique is that they don't have to move through any medium, or substance, in between. In space, it is absolutely silent because sound waves have to move through a medium. However, you can see because light is transmitted via an electromagnetic wave.

There is an inverse relationship between two factors we use to describe electromagnetic waves. Remember that they are regular, and that makes a big difference. Therefore, wavelength is inversely proportional to frequency. Wavelength is the space between two identical points on the wave. For example, if you were to measure the distance between the high points of a wave, that would be the wavelength. Frequency refers to how often a full wave passes by. The longer the wavelength, the shorter the frequency.


So, now that we know a few basic facts about electromagnetic waves, where do they come from? The simple answer is just about anywhere. Every atom in existence vibrates, and those vibrations send out electromagnetic waves. But let's be honest, that's not really the answer you were looking for. Instead, let's look at natural and man-made sources of waves.

The biggest natural source of electromagnetic waves that we encounter on a daily basis is the sun. The sun produces a huge amount of electromagnetic energy. Much of it is visible to us. However, as anyone who has ever been sunburned can attest, some of it is not visible to us, especially ultraviolet light that causes sunburns. Meanwhile, radioactive elements can send out gamma rays, which have their own issues associated with them.

But what about man-made waves? If you're watching this lesson on a wireless connection, then chances are you're making use of wifi waves. These waves have wavelengths shorter than a radio wave but longer than a microwave. Speaking of radio waves, those waves are also often man-made, although we do still get some from space we can't quite explain.

Regions of Waves

So far I've mentioned a number of different types of waves, but where do they all fit in? It turns out that all electromagnetic waves can fit on the same spectrum. It is the aptly named electromagnetic spectrum and tells us a great deal about the waves based on the frequency and wavelength of each type of wave. We'll start by describing the waves with the longest wavelength and work to those that are much shorter.

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