The Seven Types of Electromagnetic Waves

Nicholas Amendolare, Maria Howard
  • Author
    Nicholas Amendolare

    Nicholas Amendolare is a high school and middle school science teacher from Plymouth, Massachusetts. He has a bachelor's degree in environmental science from Worcester Polytechnic Institute and a master's degree in education from Harvard University. He has been a teacher for nine years, has written for TED-Ed, and is the founder of www.MrAscience.com.

  • Instructor
    Maria Howard

    Maria is a teacher and a learning specialist and has master's degrees in literature and education.

Discover the different types of electromagnetic waves and what defines an electromagnetic wave. Understand the term electromagnetic and see an electromagnetic wave diagram. Updated: 11/03/2021

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Electromagnetic Waves Definition

Electromagnetic waves are simultaneous periodic oscillations in the intensity of an electromagnetic field. Unlike traditional waves, they do not need a medium to travel through, and they travel at the speed of light. There are seven types of electromagnetic waves: radio waves, microwaves, infrared light, visible light, ultraviolet light, X-rays, and gamma rays.

What does Electromagnetic Mean?

The term "electromagnetic" simply means "related to electromagnetism." Electromagnetism refers to the two overlapping worlds of magnetism and electricity in the scientific context. Although electricity and magnetism were discovered independently, electromagnetism is now considered the fundamental physical force that explains reactions between charged particles (protons and electrons) and the release of photons (electromagnetic waves).

The first scientist to bridge the gap between electricity and magnetism was Gian Romagnosi. In 1802, he discovered that running an electric current through a battery would disturb a nearby compass needle. But it wasn't until James Clerk Maxwell, a few decades later, that electricity and magnetism were unified in a single theory. The worlds of magnetism, charged particles, protons, electrons, and electricity were finally brought together.

However, Maxwell's theories were not compatible with classical mechanics, including Newton's laws. And it wasn't until Albert Einstein's 1905 paper on special relativity that this incompatibility was fully explained. Today, we consider electricity (the flow of electrons) and magnetism (the interactions between protons, electrons, and light) to be two sides of the same coin.

Terms related to Electromagnetic Waves

There are many terms related to electromagnetism, most of which have origins in the physics of physical waves, as one might find in the ocean. The following is a brief definition of six very important terms related to the structure of waves.

  • Wavelength: Wavelength is the length of a wave, measured from crest to crest or from trough to trough. The wavelength of visible light is very small, only a few hundred nanometers.
  • Frequency: Frequency is the number of cycles that a wave experiences per unit time. Typically, frequency is measured in Hertz (cycles per second).
  • Amplitude: Amplitude is the height of a wave, measured from the middle of a wave up to the height of its crest. However, the amplitude of electromagnetic waves is a matter of intensity rather than physical height and is measured using units like volts and amps.
  • Crest: A crest is the high point in a wave. In a physical wave, this refers to maximum height. In an electromagnetic wave, this refers to maximum intensity.
  • Trough: A trough is the low point in a wave (the exact opposite of the crest). In a physical wave, this refers to the minimum height. In an electromagnetic wave, this refers to minimum intensity.
  • Cycle: A cycle is one full oscillation of a wave, from the time one crest arrives to the time a second crest arrives.

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Electromagnetic Wave Diagram

Electromagnetic waves are not invisible. Our eyes can detect them, of course. Visible light is simply one of the seven types of electromagnetic waves, the type our eyeballs can detect. Across the electromagnetic spectrum there are six other types as well. But unlike with physical waves that one might find in a pond or in the ocean, the structure of electromagnetic waves in invisible. To help imagine the shape of such waves, scientists use diagrams like the one below.

A diagram of an electromagnetic wave.

A diagram of an electromagnetic wave.

Electromagnetic waves can be visualized as pictured, with a simultaneous oscillation of the strength of both the electric and the magnetic fields. Thus, the two waves shown can be thought of as one wave with both a vertical component (electric) and horizontal component (magnetic).

The frequency of the wave would be a measure of how many times it completes a cycle in each second. The frequency of electromagnetic waves is very high, completing millions upon millions of cycles each second. The wavelength of the wave could be measured by taking a ruler (in this case, a very tiny ruler) and measuring the waves from crest to crest or trough to trough. The wavelength of electromagnetic waves are tiny, usually measured in nanometers. Finally, by measuring the frequency and wavelength, we could determine where this wave falls in the electromagnetic spectrum. It could be visible light, or a radio wave, or even an X-ray, depending on its wavelength and frequency. For more information on the types of electromagnetic waves, read the section below.

Types of Electromagnetic Waves

There are seven types of electromagnetic waves, all of which are similar periodic oscillations in the electromagnetic field. Scientists simply classify the waves based on their frequency and wavelength (which go hand in hand). Put together, one ends up with a diagram of the entire electromagnetic spectrum, as can be seen in the image.

A diagram of the electromagnetic spectrum.

A diagram of the electromagnetic spectrum

The seven types of electromagnetic waves can be thought of as seven different kinds of light. There is only one kind that our eyeballs can detect. However, it is important to note that this is a very human distinction. Some snakes can see infrared light. Some birds can detect ultraviolet light. All in all, these seven types of waves are fundamentally the same. The only difference is their frequency and, ultimately, their effects.

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Frequently Asked Questions

What are the seven electromagnetic waves?

The seven types of electromagnetic waves are radio waves, microwaves, infrared light, visible light, ultraviolet light, X-rays, and gamma rays. The preceding list is in order from lowest frequency and least energetic (radio waves) to highest frequency and most energetic (gamma rays).

Are electromagnetic waves mechanical waves?

Electromagnetic waves are not mechanical waves. They do not travel through a medium and they do not have mass. They do carry energy, however.

What is the meaning of electromagnetic waves?

Electromagnetic waves are simultaneous periodic oscillations in the intensity of an electromagnetic field. One probably knows them better as "light."

Are electromagnetic waves transverse?

Electromagnetic fields are indeed transverse waves. This means that they travel in a direction perpendicular to their direction of oscillation.

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