eli5: What is electromagnetic radiation?
In: Physics
Two hundred years or so ago, James Clark Maxwell was coming up with a bunch of equations to describe how electricity and magnetism are related. During this, he came to a rather bizarre conclusion. He realized that magnetic and electric fields could actually self-perpetuate; they could sustain themselves without a nearby magnet or electric device. They could propagate as a wave, with no need for nearby wires or magnets. He also concluded that, in air, these waves would travel at 299,700,000 meters per second.
This is electromagnetic radiation – an alternating magnetic and electric field traveling independently of a wire or magnet.
Being a wave, this electromagnetic radiation can have frequency. When experiments showed that visible light also travels at this speed of maxwell’s waves, it began to seem as if light was also this electromagnetic radiation, but at a much higher frequency (more waves per second). This is indeed the case.
Colors of light that we can’t see. Some of these colors are really good at going though objects, kind of like when you can see a flashlight under a blanket.
[Photons](https://en.wikipedia.org/wiki/Photon). Radiation is a wave-particle situation. It is a result of photonic decay.
The word “radiation” comes from the term “radiate”, or “give off”.
Some subatomic particles bond together to create an atom, atoms that are larger are not very stable, they are basically unstable atoms, the more massive the atom the more unstable it is. That is why heavier elements are more radioactive.
When an atom is unstable, it gives off and radiates. Think of it like this: you take a very heavy bucket overfilled with water, it is too heavy and it is unstable in your arms. The bucket begins to leak out water because the way you are holding it is unstable. It keeps shaking in your arms because it’s too heavy for you to hold. This is a similar situation with very heavy elements with massive nuclei.
The heavier the element, the more protons and neutrons the nuclei is comprised of. And you can’t really pack the nucleus too much or else it will become extremely unstable and leak out particles, those particles are photons.
And now you have a radioactive atom.
A radioactive nuclei, a heavy element, will decay Gamma Rays. Gamma Rays are at the very end of the electromagnetic spectrum, making it the most lethal type of radiation. Gamma Rays are the shortest wavelength. Gamma Rays have the energy to strip electrons from the atom completely. This is why X Rays and Gamma Rays are dangerous for life forms. Because the chemicals in their bodies break apart. This is because the wavelength is short enough to disassemble covalent bonds of electrons.
Photons also decay from Electrons. When in Electron loses a bit of energy and transitions to a lower energy state, it decays a photons from itself. When a photon collides with an electron it rises up to a higher energy state and is back to the state it was in previously.
[Here](https://youtu.be/IXxZRZxafEQ) is a 4 minute video explaining the origin of light and radiation.
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