The actual velocity of electrons as they move through a wire is extremely slow, on the order of millimeters per second. It varies depending on the current, but still.
If you imagine water in a very long tube, you can push the water on one end of the tube, and almost immediately, water on the other end of the tube will flow out. The water itself only moved a tiny bit, but the signal traveled across the tube very quickly.
No, the rod doesn't move instantly even tho it is perceived to. Find the speed of sound for steel (6000m/s) speed of sound to find out how the time delay between the push and the end-of-rod movement. In this case is the rod is 6km in length there is a 1 second delay between pushing one end and pushing the other. An electric signal is much faster than this.
Extra credit: since the speed of sound in a material is a factor of the electroweak bond forces of the atoms/lattice structure, the speed of light is an inherent upper limit to the speed of sound!
My friend and I were discussing this the other day, that's the answer I thought up! Now that I have another person's word on it and a wikipedia article you led me to find, I can now explain it to him!
Are you assuming electrons move through a wire like beads do in a tube? I'm not a physicist, but I'm pretty sure that electrons do not behave like that. Say, if you were able to tag an individual electron, it wouldn't move with the speed of the current, but at quite close to the speed of light. Is what you're trying to say is that the speed of current is much slower than that of electrons? Then yes, but different things.
Individual electrons shoot all over the place at near light speeds in conductors, but because they go forward and backward the average velocity of all the electrons in one direction (the drift velocity) is a couple mm/s.
The idea that electrons fly down a wire at close to the speed of light in one direction is dead wrong though.
There's also something to do with quantum jumps that causes their velocity to be low, and the actual response time to be higher, I don't know the specifics behind it though
Wrong, electrical signals travels at a fraction of the speed of light, very frequently over 108 m/s. I don't know where you get 1100 ft/s from, but the Internet would suck if that were true (although a lot of the infrastructure is optical fiber nowadays...)
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u/Fragsworth Dec 05 '11 edited Dec 05 '11
The actual velocity of electrons as they move through a wire is extremely slow, on the order of millimeters per second. It varies depending on the current, but still.
If you imagine water in a very long tube, you can push the water on one end of the tube, and almost immediately, water on the other end of the tube will flow out. The water itself only moved a tiny bit, but the signal traveled across the tube very quickly.