That is my question.
Roughly speaking, the speed of light. Minus some “friction” and dependent on the medium it moves through, but basically the speed of light.
Interestingly, the answer varies depending on how you define electricity. We all know that electric current is result of the movement of charge (electrons) around a circuit, but the fact of the matter is that the speed of electron movement is actully pretty slow - on the order of 10 cm/sec (IIRC, it is a 10 years since I did the experiment as an Undergrad student). This site agrees with my guess.
Why then, does the light-bulb light up as soon as the switch is flipped? Because the electric field travels at the speed of light, and so the “command” to move reaches the electrons near the light instanly, while the electrons that were near the switch may take several seconds to actually reach the light-bulb (I am assuming DC current here!!)
Gp
Grimpixie
You got it right, I posted something in the duplicate thread of this OP but not with the accuracy or economy of words you have, I am not worthy.
Duplicate thead. See http://boards.straightdope.com/sdmb/showthread.php?threadid=88400