Question about electrons and voltage

Charge is not voltage; they have different units.

Only macroscopic objects, like chunks of metal, have voltages.

If you had two parallel pizza plates floating in space, electrically neutral, and yanked an electron out of one and stuck it to the other, then you'd have a voltage between the plates.

The voltage between those pizza plates would be

V = Q / C

where V is in volts Q is the charge you moved C is the capacitance between plates.

For, say, 20 pF capacitance between the floating pizza plates, for every electron you drag across, the voltage between the plates increases by 8 nanovolts.

If you connect a wire between the charged plates, all those electrons zoom back home along the wire and the plates again become relatively neutral, no voltage. The zooming-back flow is "current."

Interesting: One electron can make a lot of volts if it's used to charge a very small object. I wonder if the concept "capacitance of an electron" has any meaning. If it did, the electron itself could be said to have a voltage. A *big* voltage!

John

How many volts-per-meter is the electric field of one 1 Hz photon?

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How many inches do you weigh?

A photon does have a traveling electric field, and that field intensity could be measured in v/m, although it is spatially and temporally complex. Not a problem I'd care to formulate.

The energy that photon is packing is 6.6e-34 joules. And the photon is big, would barely fit between the earth and the moon. Energy density looks fairly low.

John

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I plugged 6.6e-34 joules into the above website and got a measure of

4.1194e-15 electron-volt. Does this mean that the electric field of one 1 Hz photon has a strength of 4.1194e-15 volt per meter?

No. It means that it has an energy of 4.1194e-15 electron-Volts, i.e. the same energy as would be required to move a single electron up a 4.1194e-15 Volt potential gap, or the same energy as would be gained by an electron accelerating down a 4.1194e-15 Volt gap.

One Joule is one Coulomb-Volt (one Volt is defined as one Joule per Coulomb). An electron-Volt is the same concept but for the charge on a single electron rather than a charge of one Coulomb. Distance units don't come into it.

A way to see that distance doesn't come into it without just accepting the statement as fact from someone is to imagine two plates separated by some arbitrary distance of vacuum -- call it one meter -- and with a voltage potential across them -- call it one volt. Then imagine releasing an electron from the surface of the plate with the more negative potential. The electron accelerates over the distance and eventually strikes the positive plate. At the time of impact, there is 1/2 m v^2 kinetic energy (or 1 eV, here) to disperse. Now imagine separating the plates by 10 meters, keeping the 1 volt potential difference. The acceleration will be ten times slower, but the distance is 10 times further, so the final velocity is the same in both cases. The distance doesn't matter, in the end.

(If there were a Coulomb's worth of electrons involved, the sum of their kinetic energies would be a Joule if accelerated by a 1 volt potential difference, regardless of distance.)

Jon