What do they have to do with magnets? Are really strong magnets capable of bending the whole spectrum or something? Is the radiation itself magnetic?
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Electricity and magnetism are related, just look at maxwells equation.
The simples relationship is a change in the magnetic field creating an electrical current in a wire, a change in electrical current creates a changing magnetic field. If the changing magnetic field is made by rotation a magnet we are not describing how an electric generator works. The same generator works as a motor if you provide the electricity from another source.
You can create them in a multiple-way one it to run an electric current that changes over time through the wire, the current produces a magnetic field around the wire and both there produce electromagnetic waves that move away from the wire. This is how an antenna works in your cellphone.
If you instead of a changing electric current in a wire create a changing magnetic field by moving a magnet you create electromagnetic waves too. The problem is that there is a limitation on how fast you can accelerate a magnet. To create waves like the lower frequency range of cellphones you need to move it up and down 700 million times in a second. move it up and down 500 trillion times per second and it emits visible light So for practical purposes you do not do it that way.
It is possible to do something like that https://en.wikipedia.org/wiki/Goldschmidt_alternator or https://en.wikipedia.org/wiki/Alexanderson_alternator that generates low-frequency radio waves by mechanically rotating discs at high RPM with multiple magnets/hold for magnetic filed in discs. We talk about frequencies in the 20kHz to 100kHz range. They were abandoned when you could use the electrical system to do the same thing.
An electromagnetic wave is a change in both magnetic and electrical fields. A common illustration of this is images like https://commons.wikimedia.org/wiki/File:Electromagnetic_waves.png the fields are 90 degrees apart and have a direction in space. It is not just an illustration but describes what we observe.
Light polarization is the direction of the electric waves and is used for example in sunglasses to block out light reflected light. Light reflected from something like a road in front of you will primary be polarised in one direction because of the physical orientation fo the surface of the ground
Electricity and magnetism are two sides of the same coin. For waves of one to exist, they have to be paired with waves of the other. This means that light is a wave with both electric and magnetic components.
Electromagnetic waves are just electric and magnetic fields wiggling.
If you wiggle a magnet up and down really fast, the “pull” of that magnet a metre away will get weaker and stronger as you wiggle it. The magnet’s “pull” wiggling will travel through space as a radio wave.
Similarly, if you charge a balloon with static electricity by rubbing it on your hair, then wiggle the balloon really fast, the “pull” of the balloon on your hair will get weaker and stronger. This wiggling of pull strength will also travel through space as a radio wave.
Electromagnetic waves in general – light, gamma waves, radio, microwaves – are all just the strength of magnetic (and electric) “pull” getter stronger and weaker in space.
**TL;DR:** Wiggling a magnet makes light.
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