# Electricity is magnetism

By: Etienne Lorrain (etienne_lorrain.delete@this.yahoo.fr), December 17, 2021 2:44 am
⚛ (0xe2.0x9a.0x9b.delete@this.gmail.com) on December 16, 2021 5:22 pm wrote:
> Adrian (a.delete@this.acm.org) on December 15, 2021 4:06 am wrote:
> > Brett (ggtgp.delete@this.yahoo.com) on December 14, 2021 3:01 pm wrote:
> > > Electricity is magnetism:
> > > https://youtu.be/bHIhgxav9LY
> >
> > So the video just plays with words and it presents normal circuit behavior as unexpected.
> >
> > The only right part of it is stressing that if you have a circuit with parts close to the power
> > supply and parts very distant to it, the electromagnetic field will propagate instantaneously to
> > all the near parts, so conduction in them can start immediately, while the distant parts, regardless
> > where they are placed in the circuit, will behave as long lines so at their insertion point in the
> > circuit they might have an inductive, capacitive or resonant behavior. Depending on the details
> > of the circuit, the bulb may light immediately as in the video, or not, in other cases.
>
> Assuming the circuit is built as imagined in the video (that is: the shortest distance between the light
> bulb and the power supply is 1 meter; c = 300e6 m/s; 1/c = 3.3e-09; the total length of the cables in
> the circuit is [left+right = c+c = 2*c = 600e6 meters]): What is the minimum voltage of the power supply
> in order for the light bulb to reliably emit 1 photon in 1/c seconds after closing the switch?

>
> -atom

You forgot a lot of other assumptions:
- the battery can provide your electrons at the speed of light, any quantities of them (not a chemical battery).
- The light bulb will emit a photon as soon as it receives enough electrons (not an incandescent light bulb) and there aren't any external radiation in the system which would emit a photon.
- The switch can go from OFF to ON at the speed of light, without any setup time.
- The electron will "travel" at the speed of light in the copper wire. There isn't any metal/metal interface, all conductors are "copper" even inside the battery.
...
In short you are looking at a problem from a fundamental physics point of view, you can try to get a better understanding of the "world around us" with such assumptions, but if you want to see what really happens if you try to build it - then you need to look at the problem from an engineer point of view.

In the later point of view, for the first few nanoseconds, you can ignore the wires on both sides are connected after a very long distance. Engineers will say there is a capacitors in between cables at 1 meter distance, the closing switch generate an edge of voltage which can be represented by an FFT (with very high frequency components), and very high frequencies do pass through capacitors - so you may detect few electrons at your light bulb - but you would better use a very efficient electron detector...
TopicPosted ByDate
Electricity is magnetismBrett2021/12/14 04:01 PM
*facepalm* (NT)Ray2021/12/14 05:16 PM
in fairness what started out trollish turned into a really informative thread (NT)anonymous22021/12/15 06:55 PM
Electricity is magnetismAnon2021/12/14 06:16 PM
Electricity is magnetismLightning2021/12/14 06:47 PM
Electricity is magnetismDavid Hess2021/12/14 10:47 PM
Electricity is magnetismBrett2021/12/15 12:12 PM
Electricity is magnetismSimon Farnsworth2021/12/15 02:30 PM
Electricity is magnetismAnon2021/12/15 03:03 PM
Electricity is magnetism---2021/12/16 12:19 PM
Sorry for a few typos, I was in a hurry, but the typos do not affect the meaningAdrian2021/12/15 05:40 AM
Electricity is magnetism2021/12/16 06:22 PM
Electricity is magnetismEtienne Lorrain2021/12/17 02:44 AM
Electricity is magnetismBrett2021/12/17 01:44 PM
Electricity is magnetism2021/12/17 02:49 PM
Electricity is magnetismanon12021/12/19 03:51 AM