Something we often study in physics and science is light and electromagnetic radiation (EMR). These are things that apply commonly in our life, most notably colors and what we can see. But there are also less widely known types of electromagnetic radiation that really change our lives such as X-Rays and radio waves.
In this article, we’ll go through the types of electromagnetic radiation, in other words, the EMR spectrum.
What Is The EMR Spectrum
The electromagnetic spectrum is the term applied to all the types of EMR considered together in terms of frequency, wavelength, or energy. All parts of the electromagnetic spectrum, with varying intensity, are found in our daily lives. Like mentioned in the introduction, visible light is one of the most commonly known.
Other types of EMR include the infrared spectrum which is sensed as heat and the ultraviolet range which provides for radiation that can damage living cells, often causing a physiological response such as sunburn. Here’s a diagram comparing different EMR.
Let’s get into the types of EMR from the lowest energy waves to highest.
Radio and Radar
Radio and radar waves have a very low relative energy. Their wavelengths range from about ten to the power of 4 to ten to the power of negative two meters and the frequencies hover around ten to the power of four to ten to the power of ten Hertz.
These waves are produced by oscillating electrons in an electric circuit like an antenna, and its long wavelength allows a large amount of diffraction is making it useful for long-distance communication, for example, a PC broadband. Other uses include broadcasting radio, for example, the news you hear in your car.
These radio and radar waves do have some problems though. Although they won’t be causing death or destruction of cells, it does require government regulations to control transmission and avoid interference especially when the use is significant such as plane communication and transmission.
The next lowest energy wave on the electromagnetic spectrum are microwaves. These waves have a general frequency of ten to the power of nine to ten to the power of twelve hertz and a wavelength of ten to the power of negative one to ten to the power of negative four meters.
Microwaves are produced through the oscillation of electrons in special tubes and solid-state devices. Their shorter wavelength reduces diffraction for short-distance communication. Certain types of microwaves’ frequencies actually match the natural resonant frequency of water molecules which allows it to heat water molecules up and hence, the microwave. Another use of microwaves is in cell phones where the use of microwaves is easier in shorter distance communication.
Some of you may have seen those reports were overeating microwaved food can lead to cancer. While there isn’t solid proof where microwaves do cause cancer, but they still may be linked to some forms of cancer. Direct exposure to these waves can cause harm. If the intensity of the waves is high enough, there will be damage caused to the living tissue due to the heating of water molecules within tissues.
The next type of EMR is infrared radiation. Its frequency ranges from ten to the power of eleven to four times ten to the power of fourteen hertz. Its wavelength sits around ten to the power of negative three to seven point five times ten to the negative seven meters. Their relative energy is also low.
Infrared waves are created by the motion of particles; namely the transitions of valence electrons in atoms and molecules. Like the microwave, this type of radiation also causes objects to become warm but not because of water. Just about everything emits infrared radiation which you can feel from people and other mammals. Solid objects such as stone still emit infrared radiation but at little amounts and very inefficiently.
Have you ever seen chicks (baby chickens) huddled in places with glowing red lights? One of the uses of infrared radiation is to heat things up just as those chicks are warmed. Other than heating things up, infrared radiation isn’t used as much as it is detected. Remote sensing and night vision scopes detect infrared radiation to function and “see” different things when you don’t have the eyes to look or if it’s too dark.
Infrared waves are heat. It’s generally harmless until the heat goes up to the point where it can significantly burn you.
Have you heard of the acronym ROY G BIV? This is the order of waves in the visible light spectrum from low energy to higher energy or in simpler terms, the order of colors in a rainbow. The relative energy overall of the visible light spectrum is medium, the frequency sits at around four times ten to the fourteen to seven point five times ten to the fourteen hertz, and the range of wavelengths is from seven points five times ten to the negative seven to four times ten to the negative seven meters. Each of the colors does have their individual wavelength and frequency waves which I will list here:
- Red: 740-625 nanometers (nm)
- Orange: 625-590 nm
- Yellow: 540-565 nm
- Green: 565-500 nm
- Blue: 500-450 nm
- Indigo: 450-420 nm
- Violet: 420-390 nm
Just a disclaimer, these are relative wavelength ranges that I studied and not absolute. Those ranges are approximate and exact differences are hard to discern just like how many people would argue over whether something is red or orange.
Also a general note of why I didn’t list the frequencies compared to when I was talking about the other waves. This is because we know that one of the equations of speed is that it’s equal to wavelength times frequency and because we know the speed of light to be about three times ten to the power of eight meters per second, knowing either the frequency or wavelength will allow us to calculate the other missing factor.
Thus, knowing all these wavelengths allows you to calculate the frequency yourself.
Do you want to know how waves in the visible light spectrum are created? They actually come from higher-energy transitions involving valence electrons in atoms. The reason we can see things is because these waves actually reflect off of different items and things we can’t see, such as atoms, are a result of light diffracting around these small objects instead of reflecting.
Light waves limit the size of objects we can see because they just can’t bounce off of objects that are too small.
Ultraviolet waves have high relative energy, and they’re created through even higher-energy transitions involving valence electrons in atoms. The frequency of ultraviolet waves hover from seven point five times ten to the power of fourteen to seven point five times ten to the power of seventeen hertz and the wavelength ranges from four times ten to the negative seven to four times ten to the negative nine meters.
Ultraviolet waves are easily absorbed by objects which causes fluorescence of some materials and tanning of humans. Sometimes it is also used to kill bacteria.
These waves are what causes sunburn, and prolonged exposure can cause mutations and cancer in humans.
X-Rays have very high relative energy, and they are made by transitioning electrons in an atom or the sudden acceleration of high-energy free electrons. They have a frequency range of ten to the power of seventeen to ten to the power of twenty Hertz and a wavelength range of ten to the power of negative nine to ten to the power of negative twelve meters.
Have we all heard of an x-ray before? Like the kind where they check your bones for breaks or mishaps? The reason x-rays can do this is because it penetrates most matter but is absorbed by denser material such as bone or metal. Along going to the doctors to check your fractured wrist, x-rays can also destroy carcinogenic or mutant cells.
Although x-rays have been harnessed to a significant degree of safety, exposure to too much can cause mutations and cancer in humans.
The relative energy of these waves starts to get extremely high with gamma waves. Their frequency has a range from ten to the power of nineteen to ten to the power of twenty-four hertz and a wavelength range of ten to the power of negative eleven to ten to the power of negative sixteen meters.
Gamma rays are usually made from the decomposition of unstable nuclei, either spontaneously or by the sudden negative accelerations from high-energy particle accelerators. These rays penetrate matter very deeply and can destroy carcinogenic or mutant cells on a local scale. Generally, they’re used to probe the structure of matter and in industrial imaging.
Because these waves are so powerful, they can cause radiation sickness and even death.
Cosmic waves have the highest relative energy until we find out about even more powerful EMR. They have a frequency of ten to the power of twenty-four hertz or higher and a wavelength of ten to the power of negative sixteen or less.
This type of radiation is created by the bombardment of the Earth’s atmosphere by extremely high-energy particles from space. These waves penetrate matter extremely deeply and studying of these cosmic rays allow investigators to formulate ideas about the universe.
Because these waves are so powerful, they can cause radiation sickness and death.
Of course, I didn’t go into much detail on any of these waves. I’m just showing the electromagnetic radiation spectrum. If you want more about each wave or have any questions, leave them down below! I would love to hear what you want to say.
For now, go learn some more and have a great day!