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
The Seven Types of Electromagnetic Waves
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.
Heinrich Hertz and Electromagnetic Waves
Who is Heinrich Hertz? If you guessed that he was the founder of the popular American car rental company with a similar name, you're not alone. But Heinrich Hertz wasn't a car rental entrepreneur. Instead, he was a German scientist who performed experiments with electricity when electricity was still a fancy new thing that scientists had a lot to learn about.
In 1888, when Hertz was 30, he made an electric spark jump from one terminal to another and noticed a second spark at the same time between two terminals a couple of yards away. Exciting stuff, I know, but this was 1888, and what Hertz noticed was a different kind of electromagnetic wave that eventually came to be known as Hertzian waves.
A few years later, in 1896, a young Italian scientist named Guglielmo Marconi built on Hertz's discovery and created the first radio transmitter, sending radio signals for a mile. (A mile!) Hertzian waves are now called radio waves and are used every day, from listening to the radio to watching TV.
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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.
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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.
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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.
Radio Waves
Radio waves are low-frequency, long-wavelength electromagnetic waves. They are the least energetic type of electromagnetic wave. Their wavelength is defined as any wavelength above 1 millimeter, and their frequency is defined as any frequency below 300,000,000,000 Hertz.
Microwaves
Microwaves have a higher frequency and shorter wavelength than radio waves. Their wavelength is defined as any wavelength between 1 millimeter and 25 micrometers, and their frequency is defined as any frequency between 300,000,000,000 and 10,000,000,000,000 Hertz.
Infrared
Just above microwaves, with a slightly higher frequency and slightly shorter wavelength, is a type of light called infrared light. Infrared wavelengths are defined as any wavelength between 25 micrometers and 2.5 micrometers, and their frequency is defined as any frequency between 10,000,000,000,000 and 400,000,000,000,000 Hertz.
Visible Light
Just above infrared light is visible light. It is not fundamentally different from infrared, but it has a high enough frequency that it can be detected by the human eye. It comes in a variety of colors (red, orange, yellow, green, blue, purple, etc.) that all correspond to different frequencies. The wavelength for visible light varies from 400 to 750 nanometers, and the frequencies are between 400,000,000,000,000 and 750,000,000,000,000 Hertz.
Ultraviolet Light
Beyond visible light, with just a slightly higher frequency, is ultraviolet light. Ultraviolet light cannot be detected by the human eye, but it is absorbed by the human skin and used in the production of Vitamin-D. The wavelengths for ultraviolet light vary from 1 to 400 nanometers, and the frequencies are between 1,000,000,000,000,000 and 100,000,000,000,000,000 Hertz.
X-rays
Beyond ultraviolet light are x-rays. They have a higher frequency, carry more energy, and have shorter wavelengths. They can also be dangerous, capable of damaging human cells and causing cancer. The wavelengths for X-rays range from 1 nanometer to 1 picometer, and the frequencies are between 100,000,000,000,000,000 and 100,000,000,000,000,000,000 Hertz.
Gamma-Rays
Gamma rays are the highest-frequency type of electromagnetic radiation. They are also the most dangerous. They have a very small wavelength, a high frequency, and each photon carries a huge amount of energy. Gamma rays can be very harmful to humans in high amounts. The wavelengths for gamma rays are classified as anything less than 1 picometer, and the frequencies are anything above 100,000,000,000,000,000,000 Hertz.
Lesson Summary
Electromagnetic waves are periodic oscillations in the intensity of an electromagnetic field. They come in seven types: radio waves, microwaves, infrared light, visible light, ultraviolet light, X-rays, and gamma rays. One can think of them as seven different kinds of light. And although only one is detectable by the human eye, they are involved in everything from the production of Vitamin-D (ultraviolet light) to the sending of signals over Bluetooth (radio waves).
Discoveries in modern physics have illuminated the fact that electricity and magnetism are simply two sides of the same coin. Electricity is the flow of charged particles called electrons, Magnetism is the interaction between charged particles (electrons and protons). Electromagnetic waves are simply changes in the arrangements of charged particles, which have a wave of reverberating through space and time. Electromagnetic waves are studied using some of the same terminology as physical waves (wavelength, frequency, amplitude, crest, trough, cycle, etc.). They are also categorized by their frequency and wavelength into the seven types mentioned above.
What are Electromagnetic Waves?
We are surrounded by waves we can see and hear, from ocean waves to sound waves. A wave shows the transfer of energy, from the wind that starts an ocean wave to the sound that moves through the air to your ear drum. Waves that pass through a physical object or medium are called mechanical waves. Unlike mechanical waves, electromagnetic waves do not need a medium to travel or propagate. Electric and magnetic fields both produce vibrations and, together, the two types of energy create electromagnetic waves.
Waves take different shapes, but electromagnetic waves all have a snake-like shape which makes them transverse waves. Transverse waves are measured by their height, or amplitude, and by their wavelength, or the distance between the highest point of one wave, the crest, to the crest of the next wave. The lowest point of a wave is called a trough. Trough to trough can be measured, too. When analyzing an electromagnetic wave, both the amplitude and distance between waves is measured.
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One whole wave, from crest to crest, or trough to trough, is called a cycle. The number of cycles that occur per second is the wave's frequency. In honor of Heinrich Hertz, we measure frequency in hertz or Hz.
Types of Electromagnetic Waves
Electromagnetic waves are ordered on the electromagnetic spectrum by frequency. They range from radio waves with fewer cycles per second to the extraordinarily fast and harmful high frequency of gamma rays.
Radio waves have the lowest frequency of the seven bands of waves on the electromagnetic spectrum, which also means they have the least amount of energy. Radio waves have wavelengths measuring from miles to the length of a football, or around 11 inches.
It is common to talk about the frequency of radio waves, or the number of waves per second. When tuning in to a radio station, a person is listening to a specific frequency of radio waves. AM stations are numbered from 520 to 1610, with each number representing the frequency of the station at thousands of hertz per second, or kilohertz, abbreviated kHz. FM station frequencies range from 87.0 to 107.9 million hertz per second, called megahertz or MHz.
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Next on the spectrum are microwaves, a type of radio wave that are less than 11.8 inches long. The microwaves people use to heat food have waves measuring about five inches. Microwaves aren't just for heating leftovers or cups of coffee, though. Microwaves are also used for radar, television and satellites.
Microwaves occur at higher frequencies, with billions or even trillions of cycles occurring per second. Since writing out 4,000,000 hertz is kind of clunky, it would be written as 4 gigahertz or 4 GHz. Digital radio is broadcast at a frequency of 2.5 billion hertz per second, or 2.5 GHz.
Infrared waves occur at an even higher frequency than microwaves. Infrared waves are used to power television remote controls and for thermal imaging, like when using a pair of night vision goggles. When you feel warmed by the sunlight, the energy you feel is infrared radiation from the sun. Since infrared waves have such high frequencies, their wavelengths are so tiny they are only hundredths or thousandths of an inch.
All electromagnetic waves are light, but the band of the electromagnetic spectrum that people and animals can see is called visible light. When a beam of light passes through a prism, a person can see each color of the rainbow separated into their individual wavelengths. Red, the longest of the wavelengths, measures around 700 nanometers; yellow is around 600 nanometers; and violet, the shortest, is around 400 nanometers in length.
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After visible light, it is now back to electromagnetic waves, which humans can no longer see. Ultraviolet waves or UV waves measure between 400 and 1 nanometers and occur at very high frequencies, often more than 1,000 trillion cycles per second. You might have heard of UVA and UVB waves, since they are the type of waves sunblock protects against. There is a third type of UV waves, UVC, which are absorbed into the Earth's atmosphere. A little UV light is good for you, though, since it provides your body with the ability to produce vitamin D.
The next type of wave is the x-ray. If you have ever broken a bone, or thought you might have broken a bone, you probably were given an x-ray. X-rays have such small wavelengths that scientists start to think about them as particles of energy called rays instead of waves. At one million trillion wavelengths per second, x-rays provide such strong bursts of energy they can kill cells in your body.
Lastly on the electromagnetic spectrum are the gamma rays. Gamma rays are powerful enough to break the bonds between molecules. They are the waves emitted into the air when the nuclear bombs explode. Gamma ray bursts, made by supernovas billions of light years away in space, are several times brighter than our sun.
Lesson Summary
Waves are all around us. Electromagnetic waves do not need a medium to propagate through. Electric and magnetic fields both produce vibrations and, together, they create electromagnetic waves. Electromagnetic waves are transverse waves, meaning they are measured by their amplitude and their wavelength. In the late 1800s, Heinrich Hertz and Guglielmo Marconi conducted experiments with electricity that led to the discovery and use of radio waves. Today, the seven types of waves are represented on the electromagnetic spectrum. The spectrum ranges from low-frequency radio waves to the strong and high-frequency gamma rays. In between the two are the other types of waves, including the familiar microwaves that are used to heat food and visible light that humans can see. Like gamma ray bursts, each band on the electromagnetic spectrum allows us to learn something new about the universe.
For example, infrared waves show the heat from other planets, moons and stars. The ultraviolet waves (UV) allow us to learn more about hot stars, and x-rays allow us to find gas clouds in space.
Electromagnetic Waves Key Terms
 |
- Heinrich Hertz & Guglielmo Marconi: conducted experiments in the late 1800s with electricity that led to the discovery and use of radio waves
- Electromagnetic waves: a combination of electric and magnetic fields
- Radio waves: waves used for listening to the radio or watching TV
- Hertzian waves: electromagnetic/radio waves
- Wave: shows the transfer of energy
- Mechanical waves: pass through a physical object or medium
- Transverse waves / amplitude: measured by their height
- Wavelength / crest: the distance between the highest point, crest to crest, of one wave
- Trough: lowest point of a wave
- Cycle: one whole wave, from crest to crest, or trough to trough
- Frequency: number of cycles that occur per second
- Hertz or Hz: measurement of frequency; thousands - kilohertz (kHz), millions - megahertz (mHz), billions - gigahertz (GHz)
- Electromagnetic spectrum: the order of electromagnetic waves by frequency: (lowest) radio waves (communication), microwaves (heat food), infrared waves (remote controls), visible light (what humans can see), ultraviolet rays (dangerous sun waves), x-rays (controlled medical use), (highest) gamma rays (radioactive)
- Rays: particles of energy
- Gamma ray bursts: made by supernovas billions of light years away and are several times brighter than the sun
Learning Outcomes
After your completion of this lesson, determine whether you recall enough to:
- Identify Heinrich Hertz and discuss his work with electromagnetic waves
- Note the characteristics of electromagnetic waves
- Name several types of these waves
To unlock this lesson you must be a Study.com Member.
Create your account
Video Transcript
Heinrich Hertz and Electromagnetic Waves
Who is Heinrich Hertz? If you guessed that he was the founder of the popular American car rental company with a similar name, you're not alone. But Heinrich Hertz wasn't a car rental entrepreneur. Instead, he was a German scientist who performed experiments with electricity when electricity was still a fancy new thing that scientists had a lot to learn about.
In 1888, when Hertz was 30, he made an electric spark jump from one terminal to another and noticed a second spark at the same time between two terminals a couple of yards away. Exciting stuff, I know, but this was 1888, and what Hertz noticed was a different kind of electromagnetic wave that eventually came to be known as Hertzian waves.
A few years later, in 1896, a young Italian scientist named Guglielmo Marconi built on Hertz's discovery and created the first radio transmitter, sending radio signals for a mile. (A mile!) Hertzian waves are now called radio waves and are used every day, from listening to the radio to watching TV.
What are Electromagnetic Waves?
We are surrounded by waves we can see and hear, from ocean waves to sound waves. A wave shows the transfer of energy, from the wind that starts an ocean wave to the sound that moves through the air to your ear drum. Waves that pass through a physical object or medium are called mechanical waves. Unlike mechanical waves, electromagnetic waves do not need a medium to travel or propagate. Electric and magnetic fields both produce vibrations and, together, the two types of energy create electromagnetic waves.
Waves take different shapes, but electromagnetic waves all have a snake-like shape which makes them transverse waves. Transverse waves are measured by their height, or amplitude, and by their wavelength, or the distance between the highest point of one wave, the crest, to the crest of the next wave. The lowest point of a wave is called a trough. Trough to trough can be measured, too. When analyzing an electromagnetic wave, both the amplitude and distance between waves is measured.
|
One whole wave, from crest to crest, or trough to trough, is called a cycle. The number of cycles that occur per second is the wave's frequency. In honor of Heinrich Hertz, we measure frequency in hertz or Hz.
Types of Electromagnetic Waves
Electromagnetic waves are ordered on the electromagnetic spectrum by frequency. They range from radio waves with fewer cycles per second to the extraordinarily fast and harmful high frequency of gamma rays.
Radio waves have the lowest frequency of the seven bands of waves on the electromagnetic spectrum, which also means they have the least amount of energy. Radio waves have wavelengths measuring from miles to the length of a football, or around 11 inches.
It is common to talk about the frequency of radio waves, or the number of waves per second. When tuning in to a radio station, a person is listening to a specific frequency of radio waves. AM stations are numbered from 520 to 1610, with each number representing the frequency of the station at thousands of hertz per second, or kilohertz, abbreviated kHz. FM station frequencies range from 87.0 to 107.9 million hertz per second, called megahertz or MHz.
|
Next on the spectrum are microwaves, a type of radio wave that are less than 11.8 inches long. The microwaves people use to heat food have waves measuring about five inches. Microwaves aren't just for heating leftovers or cups of coffee, though. Microwaves are also used for radar, television and satellites.
Microwaves occur at higher frequencies, with billions or even trillions of cycles occurring per second. Since writing out 4,000,000 hertz is kind of clunky, it would be written as 4 gigahertz or 4 GHz. Digital radio is broadcast at a frequency of 2.5 billion hertz per second, or 2.5 GHz.
Infrared waves occur at an even higher frequency than microwaves. Infrared waves are used to power television remote controls and for thermal imaging, like when using a pair of night vision goggles. When you feel warmed by the sunlight, the energy you feel is infrared radiation from the sun. Since infrared waves have such high frequencies, their wavelengths are so tiny they are only hundredths or thousandths of an inch.
All electromagnetic waves are light, but the band of the electromagnetic spectrum that people and animals can see is called visible light. When a beam of light passes through a prism, a person can see each color of the rainbow separated into their individual wavelengths. Red, the longest of the wavelengths, measures around 700 nanometers; yellow is around 600 nanometers; and violet, the shortest, is around 400 nanometers in length.
|
After visible light, it is now back to electromagnetic waves, which humans can no longer see. Ultraviolet waves or UV waves measure between 400 and 1 nanometers and occur at very high frequencies, often more than 1,000 trillion cycles per second. You might have heard of UVA and UVB waves, since they are the type of waves sunblock protects against. There is a third type of UV waves, UVC, which are absorbed into the Earth's atmosphere. A little UV light is good for you, though, since it provides your body with the ability to produce vitamin D.
The next type of wave is the x-ray. If you have ever broken a bone, or thought you might have broken a bone, you probably were given an x-ray. X-rays have such small wavelengths that scientists start to think about them as particles of energy called rays instead of waves. At one million trillion wavelengths per second, x-rays provide such strong bursts of energy they can kill cells in your body.
Lastly on the electromagnetic spectrum are the gamma rays. Gamma rays are powerful enough to break the bonds between molecules. They are the waves emitted into the air when the nuclear bombs explode. Gamma ray bursts, made by supernovas billions of light years away in space, are several times brighter than our sun.
Lesson Summary
Waves are all around us. Electromagnetic waves do not need a medium to propagate through. Electric and magnetic fields both produce vibrations and, together, they create electromagnetic waves. Electromagnetic waves are transverse waves, meaning they are measured by their amplitude and their wavelength. In the late 1800s, Heinrich Hertz and Guglielmo Marconi conducted experiments with electricity that led to the discovery and use of radio waves. Today, the seven types of waves are represented on the electromagnetic spectrum. The spectrum ranges from low-frequency radio waves to the strong and high-frequency gamma rays. In between the two are the other types of waves, including the familiar microwaves that are used to heat food and visible light that humans can see. Like gamma ray bursts, each band on the electromagnetic spectrum allows us to learn something new about the universe.
For example, infrared waves show the heat from other planets, moons and stars. The ultraviolet waves (UV) allow us to learn more about hot stars, and x-rays allow us to find gas clouds in space.
Electromagnetic Waves Key Terms
|
- Heinrich Hertz & Guglielmo Marconi: conducted experiments in the late 1800s with electricity that led to the discovery and use of radio waves
- Electromagnetic waves: a combination of electric and magnetic fields
- Radio waves: waves used for listening to the radio or watching TV
- Hertzian waves: electromagnetic/radio waves
- Wave: shows the transfer of energy
- Mechanical waves: pass through a physical object or medium
- Transverse waves / amplitude: measured by their height
- Wavelength / crest: the distance between the highest point, crest to crest, of one wave
- Trough: lowest point of a wave
- Cycle: one whole wave, from crest to crest, or trough to trough
- Frequency: number of cycles that occur per second
- Hertz or Hz: measurement of frequency; thousands - kilohertz (kHz), millions - megahertz (mHz), billions - gigahertz (GHz)
- Electromagnetic spectrum: the order of electromagnetic waves by frequency: (lowest) radio waves (communication), microwaves (heat food), infrared waves (remote controls), visible light (what humans can see), ultraviolet rays (dangerous sun waves), x-rays (controlled medical use), (highest) gamma rays (radioactive)
- Rays: particles of energy
- Gamma ray bursts: made by supernovas billions of light years away and are several times brighter than the sun
Learning Outcomes
After your completion of this lesson, determine whether you recall enough to:
- Identify Heinrich Hertz and discuss his work with electromagnetic waves
- Note the characteristics of electromagnetic waves
- Name several types of these waves
To unlock this lesson you must be a Study.com Member.
Create your account
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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