Electromagnetism is one of those five dollar words (with six syllables!) that has the power to instantly transport us back to high school science class. But here’s the thing: you don’t have to be a physicist to understand and appreciate electromagnetism and electromagnetic energy.
Electromagnetic energy is one of nature’s fundamental forces, and it has plenty of important applications in today’s world. Get ready to learn more about how this electrifying-sounding force matters to you and the universe as we know it
What Is Electromagnetic Energy?
Also known as electromagnetic radiation, EM radiation, and electromagnetism, electromagnetic energy is a term used to describe the various energies that travel as wavelengths through space at the speed of light. EM radiation doesn’t have mass or charge. Rather, it travels in a bundle of light energy called photons
Electromagnetic energy is one of the four fundamental forces of nature — along with the strong force, the weak force, and the gravitational force. These forces have different strength levels and work across varying ranges. For example, both electromagnetic and gravitational forces have an infinite range, yet gravity is the weakest.
Electromagnetic wavelengths are measured on the electromagnetic spectrum and each has its own unique properties.
How Does Electromagnetic Energy Work?
We can think of electromagnetic waves the same way we might think of a set of waves at the beach: there are peaks and troughs that travel in a relatively regular pattern and they use energy to move
Electromagnetic radiation can be described in three ways: energy, wavelength, or frequency.
Wavelengths are typically measured in standard units, and when used to describe electromagnetic waves, it’s usually in meters (m). Going back to our beach example, the distance between the peaks of each wave is what you can consider the wavelength
The frequency of these waves are measured in Hertz (hz), megahertz (MHz), and gigahertz (Ghz), units you may be familiar with on your car radio. The higher the frequency of an electromagnetic wave, the more electromagnetic energy it carries
Interestingly, the frequency of an electromagnetic wave is inversely proportional to its wavelength, which means that the larger the frequency of such a wave, the shorter its wavelength, and vice versa
To conclude our beach metaphor, there’s one last way to measure waves, and that’s by looking at their amplitude. A wave’s amplitude—whether it’s a sound wave or one crashing on a beach—is measured by looking at the difference between the wave’s peak and its trough
What Is An Electromagnetic Field?
Electromagnetic fields are the product of EM radiation, and oftentimes are simply referred to as radiation. These electromagnetic fields can be dangerous to humans if the frequency of the EM radiation—measured in Hertz, megahertz (MHz), and gigahertz (GHz)—is too high
Magnetic fields are produced by electrical charges, and the greater that charge, the stronger the magnetic field. This has practical applications because it means that we can increase or decrease an electrical charge to fine-tune magnetic fields to our purposes
What Is the Electromagnetic Spectrum?
Not every electromagnetic wave is the same. Waves are characterized along an electromagnetic spectrum (EM spectrum) and they differ in both frequency and wavelength. While these waves can exist anywhere along a vast spectrum, they come in seven different varieties across a range of frequencies and a range of wavelengths, all of which you’ve likely heard before. As mentioned, they also have different degrees of energy.
The entire electromagnetic spectrum (going from the electromagnetic waves with the longest wavelengths to those with the shortest) is as follows:
- Radio waves
- Microwaves
- Infrared radiation
- Visible light
- Ultraviolet radiation (UV)
- X-rays
- Gamma rays
What Are the 7 Types of Electromagnetic Energy?
There are seven categories of radiation on the electromagnetic spectrum. Each has its own wavelength and frequency. Let’s take a closer look at each one and their properties.
Radio Waves
Radio waves might be the most commonly known electromagnetic wave. They have longer wavelengths (a keen reader might remember that this also means they have very low frequencies).
Radio waves are created when electric current is applied to an antenna—a metal rod—causing it to vibrate at a specific frequency and generate an electromagnetic wave with a specific wavelength.
We use radio waves all the time in our cars, but radio waves are also used in GPS positioning, television broadcasting, high-energy emissions, wireless networks, remote controls, and cell phone networks. It’s no surprise then that the low levels of radiation your cell phone emits is called radio frequency.
The next time you use your phone to make a call or your remote to change the channel, you’ll have electromagnetic radiation to thank!
Microwaves
Microwaves are a type of radio wave that also have long wavelengths and are also considered to be low frequency waveforms. Microwaves are the primary electromagnetic wave used in radar. If you’ve tuned in to your local news to see a meteorologist forecast the weather recently, you have microwaves to thank
We also use microwaves in—surprise!—microwave ovens. These work by using electromagnetic radiation to vibrate the atomic particles in your food, turning electromagnetic energy into thermal energy to heats up your meal. It’s yet another example of electromagnetic energy at work for you
Infrared Radiation
Infrared radiation is also commonly referred to as infrared light (IR, for short) or infrared waves. After radio waves and microwaves, it’s the next step down in wavelengths along the electromagnetic spectrum. These waves are invisible to the human eye, but special cameras that capture these waves can help us see at night (think night-vision goggles) or see sources of heat (thermal cameras)
Infrared radiation is also important to astronomers and researchers at NASA, who use it to detect faraway stars, or fields of gas or dust that might otherwise be invisible to even our most advanced equipment
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Visible Light
Believe it or not, visible light is a form of electromagnetic energy. These electromagnetic waves have shorter wavelengths than infrared waves or radio waves, and therefore a higher frequency—and more energy
The sun emits electromagnetic energy in electromagnetic waves all across the electromagnetic spectrum, but the visible light waves it emits are the strongest. That’s part of the reason why you can’t stare at the sun—the intensity of the visible light is too much for the human eye!
We can further differentiate visible light into the visible spectrum. Varying the wavelengths of visible light gives us all of the different colors the human eye is capable of perceiving. This is most easily understood by shining white light through a prism, which creates refraction of that light into light of varying wavelengths, and therefore the different colors of the rainbow
Ultraviolet Radiation
Ultravioletradiation (or ultraviolet light) is perhaps best known simply as UV rays. This form of electromagnetic radiation has short wavelengths, which means that ultraviolet light has a high frequency. Therefore, it contains more electromagnetic energy than visible light, microwaves, or radio waves
It’s at this point that electromagnetic radiation can start to get dangerous for humans if proper precautions are not taken. Why? Because unlike radio waves, microwaves, and infrared radiation, UV radiation is ionizing radiation. (It’s also worth noting that X-rays and gamma rays are also ionizing.)
It’s no wonder that strong ultraviolet radiation is capable of damaging our skin. As such, we use UV protection to prevent sunburn—and potentially even more serious consequences. Studies show that UV radiation is strong enough to damage DNA and potentially lead to cancer
Amazingly, the sun produces so much UV radiation that, were it not for the Earth’s atmosphere filtering out many of these harmful rays, life as we know it would not exist on land. Thank goodness for our ozone layer!
There are many practical applications for UV light, ranging from novelty items like blacklights (hello glow-in-the-dark posters!) and artificial tanning (not a good idea) to cancer treatments and surface sterilization devices
X-Rays
We’re now getting close to the tail end of the EM spectrum. While the wavelengths are growing vanishingly small, the energy and frequency of these electromagnetic waves are rising dramatically
X-rays can potentially pose dangers to living beings because this type of radiation can cause molecular damage if not tightly controlled
The most common X-ray application we all know is radiology, which uses these electromagnetic waves to produce images of the interior of the human body that would otherwise be unavailable to us. Whether you’re getting a mammogram, going through airport security, or having your teeth checked at the dentist, X-rays are a form of electromagnetic energy that we commonly interact with at various points in our lives
Gamma Rays
Gamma rays exist at the far end of the electromagnetic spectrum, with the shortest wavelengths but highest frequencies. Gamma rays are also the highest energy electromagnetic waves, and as such, they pose the largest threat to biological life
In popular culture, you may have heard of this form of electromagnetic energy in the world of comic books, where gamma rays are often included in backstories to explain how a superhero got his or her superpowers.
