[Q] Speed of electricity?

[n00b]

I know the speed of electromagnetic radiation in a vacuum is roughly 300,000 metres per second. I was wondering if anyone knows how fast the speed of electricity is as it moves through a household circuit? Presumably resistance of the copper wires would slow it down, but to what value?

[Zylatis]

Well electricity is different to EM radiation, for starters electricity is carried by charged particles which, as far as we know, all have mass and so move at less than the speed of light. I dont know a numerical answer off the top of my head but one way to calculate it would be to estimate the conditions, ie voltage across, a typical circuit, compute the associated magnetic field and then work out the magnetic force and thus the velocity of a given charged particle (for wires, electrons, for nervous systems, calcium and potassium n stuff)

 

hope that helps =)

[logy]

well it depends on what you mean by that, the time it takes from when you flick the switch for the current to reach the light bulb in the next room is close to the speed of light, each electron will "push" the next one which wll push the next one and that happens very fast.

 

the speed at which the electrons themselves move is amazingly slow and depends on resistance and voltage, but is directly proportional to curreent as by definition current is the flow of a columb of electrons per second. each electron has a charge of about 1.6 x 10^(–19) (0.000,000,000,000,000,0001,6) so each columb of charge represents about 6 x 10^18 (600,000,000,000,000,000) electrons.

for genral refference, a cubic centimeter of copper has about 8.5*10^+22 (85,000,000,000,000,000,000,000) electrons.

keep in mind that in household electricity the current is AC, alternating current so the lectrons are not flowing anywere just moving backwards and forwards !

 

this page should give you an idea about the flow of electrons in a wire;

Speed of electricity flow (speed of current.)