What is the difference between electrons and photons?

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Offline bizerl

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I've never really understood the relationship between electrons and photons. I'm told that electricity is the flow of electrons through a circuit, however I'm also told that the electro-magnetic force is quantised (is that the right word?) by the photon.

When I hear science fiction stories about advanced societies harnessing the power of light for all their technological needs i think, isn't light just a form of electro-magnetic radiation and therefore electricity? But then how does the electron fit?
« Last Edit: 07/02/2013 08:35:20 by evan_au »


Offline evan_au

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Re: What is the difference between electrons and photons?
« Reply #1 on: 07/02/2013 09:08:01 »
The electron is a particle which has a certain mass and negative electric charge. A particular electron exists at a specific position in space, travelling in a certain direction at a certain speed*.

If you accelerate an electron (eg if it passes close to a proton), it causes a disturbance in the electromagnetic field, which will propagate away from the disturbed electron at the speed of light. We call this propagating packet of energy a photon.

Electrons and photons both respond to the electromagnetic force, but they differ in:
  • mass: electron is 910−31 kg; photon is zero
  • charge: electron is negative, −1.610−19 Coulombs; photon is zero
  • speed: electron may be zero, or anything less than the speed of light; for a photon in a vacuum, it always travels at exactly the speed of light (a bit slower in denser media)
  • spin: electron: half; photon: 1
  • antiparticle: electrons have positrons; photons have themselves
For more, see: http://en.wikipedia.org/wiki/Photon  or http://en.wikipedia.org/wiki/Electron

Besides electrons, other particles of matter like protons, positrons and mesons also carry an electric charge, and have a position and velocity in space. They differ in many ways from each other, but their electric charge also makes them respond to the electromagnetic force.

*Footnote: Quantum theory says you can't exactly know its position & velocity, but that's another topic.


Offline kodyg44

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Re: What is the difference between electrons and photons?
« Reply #2 on: 22/05/2013 02:41:33 »
A photon is created when electrons return to a domestic state from a chaotic state. Valence electrons move from atom to atom, polarizing each atom and making them either positive or negative. When the electron moves back to its original atom and enters a domestic state, the electron releases a photon. I'm not totally sure why, but I hope that helped a little.