What causes electric and magnetic fields to oscillate, making light?
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Any changing electric field produces a magnetic field, and any changing magnetic field produces an electric field. In electromagnetic waves the electric field oscillates in a way that generates precisely such a oscillating magnetic field that generates the same electric field. So they kinda generate each other in a self-sustaining way.
I don’t think there’s a good answer. Mathematically we describe EM with Maxwell’s equations but like most things that are scientific theories/laws, they’re based on what we repeatedly observe. This is why scientists and physicists keep on trucking to understand what makes things happen. To me this is a quantum mechanical question but currently QM is based probabilities as we just can observe these interactions.
They are basically produced from electrons changing orbits, jumping from outer ones to inner ones, not spirally. This creates a sudden fluctuation in fields, causing a self replicating oscillation like someone has explained before. As the orbits or shells have a definite energy levels, the light frequency released is always fixed , according to what change of orbits occured. That’s why it’s always an integral multiple of planck’s constant.
EM waves are caused by accelerating charges, like an AC voltage applied to a long piece of metal (antennae). With light and higher energy rays up to X rays, they are created by electrons rapidly gaining and losing energy in an atom.
Electrons more or less “orbit” a positively charged nucleus. To pull an electron away from the positive nucleus, you need to add energy. When an electron falls back closer to the nucleus, it gives off energy in the form of light, or more specifically the orbital energy difference. In the case of a plasma, due to the thermal motion of atoms, electrons are constantly being pulled out of their orbitals and falling back in, so constantly gaining energy and losing energy and creating a glow of light.
A stationary charge has an electric field around it. If the charge moves, the field can’t move around with it instantaneously. (That would mean information about where the source charge is is travelling faster the speed of light.) But the moving charge does generate a magnetic field.
One way to think about this radiation is that it’s essentially propagating the perturbation in the electric/magnetic fields outward.
So any time you have an electric or magnetic field interact with a charged particle, because the particle moves, there’s a change in the electric/magnetic field.
The real answer: that’s a really good question. We don’t know.
Electromagnetism is fundamental as far as quantum mechanics is concerned. To give a “cause”, you would need to know something simpler and more fundamental. But physicists don’t know anything more fundamental.
All we know is what we measure. And what we measure is that they oscillate and form waves. If the wave is cohesive we call it light. If you want to know more details about *how* it oscillates, check other responses. Or go to school for physics!
Richard Feynman puts it beautifully when asked how magnets work.
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