Electromagnetic energy plays a vital part in the workings of the universe. It radiates almost everywhere, hence its alternative moniker — electromagnetic radiation.
But what is this imperceptible force? We’ll look at electromagnetic energy’s influence, from the gamma rays that powered the Starship Enterprise in Star Trek to listening to music via radio waves on our stereos. There’s also the small matter of how electromagnetic energy allows us to see visible light and how radiation is everywhere.
Let’s delve into this rich world of wavelengths, ultraviolet light, and magnetic fields and understand the attributions of electromagnetic energy.
What Is the Definition of Electromagnetic Energy?
Electromagnetic energy (EM) is also known as electromagnetic radiation or EM radiation. Both terms describe the energy that travels in waves of different wavelengths. There are many types of electromagnetic energy identifiable through their varying wavelengths. These waves are similar but are also capable of “doing” different things. We measure them on the electromagnetic spectrum.
What Are the 7 Types of Electromagnetic Radiation?
There are seven different groups of radiation wavelengths on the electromagnetic spectrum. We’ll start with the longest wavelength, with the least energy, and move along the spectrum, increasing the amount of energy and shortening the wavelength.
- Radio waves — the longest wavelength, with the least energy
- Microwave oven
- Infrared light (IR), or infrared radiation
- Visible light
- Ultraviolet radiation (UV)
- X-rays
- Gamma rays — shortest wavelength, with the most energy
For example, we cannot see the sun’s ultraviolet light that can cause sunburn, but we know UV radiation exists. We cannot see X-rays, yet we use them to provide a snapshot of our internal organs.
How Does Electromagnetic Energy Work?
To understand electromagnetic energy, imagine waves at a beach moving and crashing into the shore. Energy moves through the water — that energy is provided by wind or the Earth’s gravitational pull.
Waves of EM radiation work similarly, propagating energy as they move. To understand EM radiation better, we need to look to the atomic level.
Atoms are made of a nucleus with a positive charge that contains tiny particles called neutrons and protons. Electrons carry a negative charge and are found in an atom’s shell enclosing the nucleus.
A nucleus can become unstable when it absorbs energy; it may cause an electron to jump to a higher energy level. When the electron shifts back to its original position, energy is released as electromagnetic radiation.
Two movements now occur in a regular, rhythmical fashion called oscillation. The first movement is an oscillating electric field. The second is an oscillating magnetic field. These two “movements” travel at right angles to each other, releasing energy in the form of photon.
Photons travel as waves at the speed of light. Each photon has different traits:
- Wavelengths: the distance between a wave’s consecutive peaks
- Frequency: the number of waves within a given time
- Amount of energy
The electromagnetic wave, or energy, produced by oscillating electric and magnetic fields, could be any one of the seven types of different types of radiation listed above.
How Is Electromagnetic Energy Measured?
As we’ve seen, electromagnetic radiation is measured by its energy, wavelength, or frequency. Scientists use different measurements because of the vast difference in wavelengths.
A wave’s energy is a function of the nature of its oscillating electric and magnetic fields. An electromagnetic wave’s energy is proportional to its amplitude squared. A wave’s amplitude is the maximum extension of the oscillation of the electric and magnetic fields.
The longer, low-energy waves like radio waves are measured in frequency and expressed as hertz. Some radio wavelengths oscillate very slowly and are more than 100km in length! A medium frequency (MHz) brings music to our radios. It is between 100m and 1 kilometer in length and measures around 3MHz (3 million hertz).
Radio waves have a wide range of frequencies and can go to billions of gigahertz (GHz). One gigahertz is equivalent to 1,000 MHz, or one thousand million hertz. This range is called radio frequency (RF).
Astronomers who study radio waves at space observatories such as NASA use wavelengths or frequencies for their measurements. However, it’s hard to work with such large numbers as we move up the spectrum. The high-energy, shorter wavelengths in X-rays and gamma rays are expressed as electron volts (eV).
We can also calculate photon energies by multiplying its wave frequency by what is known as Planck’s constant.
Planck’s constant is a “’fundamental constant” — a law of physics that doesn’t change — and is the amount of energy a photon has relative to its wave frequency.
What Is the Definition of the Electromagnetic Spectrum?
Electromagnetic radiation spans an enormous range of wavelengths, which we chart on an electromagnetic spectrum. We cannot see most wavelengths, but some are visible. EM radiation, or electromagnetic radiation, is grouped on this EM spectrum according to its wavelength.
Longer wavelengths have less energy and a low frequency and include radio waves and microwaves. These low-frequency waves have the lowest energy.
Short wavelengths are found in higher energy waves like gamma rays and X-rays and have a high frequency. Gamma rays have the highest frequencies and the highest energy.
Visible light also has varying wavelengths and can help explain wavelengths. The human eye can see some wavelengths; we know the visible spectrum as the colors of the rainbow. Red light has the longest wavelength. The wavelengths get shorter as the color changes from red to orange, yellow, green, blue, indigo, and then finally to violet, which has the shortest wavelength.
Is Electromagnetic Energy Harmful?
Electromagnetic energy is also known as radiation, a word that incites caution among many people. Excessive radiation exposure can cause skin burns, radiation sickness, and cancer. It’s important to remember that radiation is a naturally occurring phenomenon; even our bodies emit radiation.Electromagnetic energy is also known as electromagnetic radiation, a word that incites caution among many people. Excessive exposure to certain types of radiation can cause skin burns, radiation sickness, and cancer. It’s important to remember that radiation is a naturally occurring phenomenon; even our bodies emit radiation.
Many electromagnetic waves are not harmful. Longer wavelengths, such as radio waves and up to visible light, do not hurt us. These are non-ionizing EM radiation types.
However, some electromagnetic energy is harmful. Ultraviolet radiation, X-ray, and gamma-ray wavelengths are called ionizing wavelengths and can be dangerous. These ionizing wavelengths are unique because they can displace electrons from atoms when they pass through matter.
Continual or intense exposure to ionizing radiation can eventually alter or damage our cells. Many people associate over-exposure to X-rays or UV radiation with increased cancer risks.
Does the Earth’s Atmosphere Protect Us From EM Radiation?
The sun is constantly emitting radiation across almost the entire electromagnetic spectrum. Most of the sun’s radiation, also called cosmic radiation, travels through free space and comes to Earth as light waves (visible light), infrared waves, and ultraviolet waves.
Some of these forms of energy are dangerous to humans and life on Earth. Fortunately, our planet’s atmosphere and electromagnetic field protect us from the more harmful waves, pushing gamma rays and UV radiation away from the Earth’s surface.
People who live at higher altitudes receive more cosmic radiation from the sun than those at sea level. Climate change, and potential holes in the ozone layer, are of great concern, especially if they let more of the sun’s gamma rays and UV radiation waves penetrate the Earth’s atmosphere.
Frequent flyers also expose themselves to more of the sun’s and other stars’ cosmic radiation during the flight. Each flight is equivalent to around the same radiation dose as a chest X-ray.
What Is the Main Source of Electromagnetic Energy?
The primary source of electromagnetic energy is the universe itself. The cosmos, its suns, and stars are sources of EM radiation, as well as galaxies and even black holes. On Earth, our primary source of electromagnetic energy is the sun.
In truth, all objects emit some form of electromagnetic energy. Radioactive elements like uranium are another source and manufactured devices like cell phones (mobile phones).
When an object absorbs more radiation than it emits, then that object’s temperature increases. If the rate of absorption is less than the rate of emission, then the object gets cooler. If more of the sun’s electromagnetic energy enters our planet’s atmosphere, then the Earth will warm.
Engineers and scientists study objects’ ability to absorb and emit radiation and how radiation reacts with matter. This branch of research is called spectroscopy.
How Does Electromagnetic Energy Travel?
We’ve seen how electromagnetic energy travels as a wave. Sound waves cannot travel through space because sound needs to vibrate air molecules to travel. Electromagnetic waves can travel through solid objects and even space. What about when electromagnetic waves encounter barriers?
Diffraction occurs when these waves collide with a barrier or when there’s a gap in the barrier. Diffraction is how the waves spread after the impact — its wavelength doesn’t change, but how it spreads does.
Think back to a transmitter broadcasting radio waves to your stereo. Transmissions with low energy and long wavelengths, such as AM stations, are much less affected by diffraction. Buildings do not overly interfere with their waves. FM stations with smaller, tighter wavelengths are more prone to diffraction. That explains why AM radio stations can broadcast over greater distances.
Refraction changes the speed of light waves when they pass from one substance to another. The change in substance density causes the light to change direction. This happens at the boundary of the two substances.
Refraction explains why objects look like they are bending, heading in a new direction when you put them in water. Try this simple experiment to witness refraction:
Put a pencil in a glass of water, and you’ll see a bend at the entry point because the two substances (water and air) have different densities.
What Are Transverse Waves in Electromagnetic Energy?
Electromagnetic waves can transfer energy.
Polarization relates to transverse waves and the direction of their oscillations. Transverse waves occur when vibrations move at a right angle to the wave’s travel direction, such as the sound waves when someone plucks a guitar string.
Longitudinal waves travel parallel to the wave’s travel direction.
How Can Electromagnetic Energy Cause Changes in Matter?
Electromagnetic energy can change an electron’s energy level or alter an atom’s motion.
Let’s put an imaginary cup of cold water in a microwave and turn the microwave oven on for 30 seconds at full power. The water absorbs the microwave’s radiation, making the water’s molecules vibrate faster and increases its thermal energy, heating the water.
Gamma rays contain more energy than any other type of EM radiation. To put that into context, scientists have recently discovered that lightning and thunderclouds release gamma rays. We can probably all agree that lightning can change matter.
Is Electromagnetic Energy Potential or Kinetic Energy?
Potential energy is stored energy and the energy of position while kinetic energy is the energy of movement.
Electromagnetic energy, in an electromagnetic field, has potential energy waiting to be released. Once moving, electromagnetic waves have kinetic energy.
Who Discovered the Theory of Electromagnetic Energy?
Scottish mathematician and scientist James Clerk Maxwell wrote his Theory of Electromagnetic Radiation in the late 19th century. He showed that electric fields, electric currents, and magnetic forces are not separate but the same thing — electromagnetic energy. He also demonstrated that electromagnetic waves and visible light were the same.
Maxwell devised Maxwell’s equations, incredibly complex mathematical equations that help us define the universe. The equations are (so far) irrefutable laws, like the law of gravity, except Maxwell’s equations relate to electric fields and magnetic fields. In short, the equations show that an electric current will create a magnetic field and vice versa.
Why Is Electromagnetic Energy So Important?
Our day-to-day lives would be very different without electromagnetic energy. We summon this often invisible energy with a flick of numerous switches. Our radio or television receives electromagnetic waves, microwaves heat our food using this energy, and infrared heat from heaters keeps us warm in winter.
We can catch sight of electromagnetic waves as light and colors when they cross our visual spectrum. These waves, whose origins lie in the tiny atomic world, are present in every part of the universe. Their micro size betrays their macro influence within the universe and your everyday life.
Brought to you by amigoenergy
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