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Electrons do actually move in a closed circuit as explained in this video: https://youtu.be/8gvJzrjwjds?t=85 They jump from atom to atom.

But what about electromagnetic waves, or more specifically radio waves. This is how I understand frequencies:

You apply an alternating voltage to some wire or coil. The back and forth alteration of the current will move electrons up and down of the wire/coil. These moving electrons cause their neighbouring electrons (in free space) to move up and down in the opposite direction of their own (as electrons repel each eachother). This goes on and on and a chain of vertically moving electrons get created which is called a wave which travels in free space. It's like swinging a rope at one end.

Am I correct? or the electrons literally move in free space like inside a circuit, from atom to atom.

Dan
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You apply an alternating voltage to some wire or coil. The back and forth alteration of the current will move electrons up and down of the wire/coil.

Your description is ok up through here.

These moving electrons cause their neighbouring electrons (in free space)

I assume by "free space" you mean the space surrounding the wire. This is already problematic since there are no free electrons outside the wire.

Let's simplify things and put the circuit in a perfect vacuum. Electrons oscillating in the circuit will still cause electromagnetic waves. So there must be something else going on.

to move up and down in the opposite direction of their own (as electrons repel each eachother). This goes on and on and a chain of vertically moving electrons get created which is called a wave which travels in free space. It's like swinging a rope at one end.

As I hinted at above, the electromagnetic wave is not carried by moving electrons.

What happens is that an oscillating electron generates an electromagnetic wave, made of oscillating electric and magnetic fields. As the wave propagates through free space, there are no electrons involved at all, simply the fields jiggling around, following Maxwell's equations. Far from the circuit that generated the wave, the wave propagates like this picture from wikipedia

enter image description here

with the electric and magnetic fields perpendicular to each other, and to the direction of motion of the wave.

Eventually, the wave may interact with some charged particles, like electrons and the energy in the wave absorbed by the particles. In that situation, the electromagnetic wave will cause the charged particles to oscillate.

Andrew
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  • there are no free electrons outside the wire I thought electrons are everywhere. The universe is made up of atoms and electrons, vacuum or not, no? – Dan Feb 07 '22 at 03:31
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    @Dan It's perfectly valid to apply Maxwell's equations to a scenario where there are no electrons outside the wire, or the density of electrons is so small they don't matter. There are still electromagnetic waves in such a case. This shows that electromagnetic radiation created by electrons oscillating in the circuit has nothing to do with electrons outside the circuit. In a lab on Earth, there are electrons everywhere, but these electrons are bound tightly to atoms, and barely oscillate at all in response to the circuit. What carries the wave are the electric and magnetic fields. – Andrew Feb 07 '22 at 03:36
  • I think my trouble in understanding the wave itself then. You are saying an EM wave is a physical thing, not related to moving electrons. What is an EM wave made up of then, is it matter? – Dan Feb 07 '22 at 03:38
  • @Dan Nope, it is electric and magnetic fields. There was an attempt in the late 1800s to explain the waves as propagating in some kind of medium called the aether. This theory was eventually recognized to be completely wrong. It is bizarre to think that electromagnetic waves are waves in a "substance" in the same way that sound waves or water waves are. But that's our modern understanding. The electric and magnetic fields carry energy from one place to another as shown in the picture from wikipedia, there is no "mechanism" underneath this picture, as far as we know today. – Andrew Feb 07 '22 at 03:41
  • I see. Sound waves are moved by air molecules hitting each other. EM waves have the same concept but we just don't know what is hitting what in this case? we just know it's moving? – Dan Feb 07 '22 at 03:46
  • Electromagnetic waves do not need to be hitting anything. They can propagate through vacuum. Electromagnetic waves are not the same as mechanical waves. – joseph h Feb 07 '22 at 04:03
  • @Dan Electromagnetic waves are not carried by ordinary matter like atoms or electrons, but we do nevertheless know what is changing and carrying energy: the electromagnetic fields themselves. The fact that the fields carry energy and waves are a propagating disturbance in the field is a very abstract and difficult concept, but it's what is implied by the math of Maxwell's equations and special relativity. – Andrew Feb 07 '22 at 04:05
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    Thanks for clearing it. – Dan Feb 07 '22 at 04:07
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    @Dan the above answer is correct, but physics has progressed since the classical electromagnetic maxwell theory, and it is proven that the electromagnetic wave is built up by an ensemble of photons in a complicated quantum mechanical way. This answer of mine tries to explain this https://physics.stackexchange.com/questions/113574/are-photons-electromagnetic-waves-quantum-waves-or-both/113588#113588 – anna v Feb 07 '22 at 04:49
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    @Dan also this https://physics.stackexchange.com/questions/638609/example-where-photon-acts-only-as-a-wave/638618#638618 – anna v Feb 07 '22 at 05:26