EEVblog 1710 - Mailbag: Tennismatic, Breadboards, Books & Boost Converters
Added 2025-09-27 05:07:19 +0000 UTCPre-release Mailbag.
Comments
I had the same misconception as you originally. But after learning more I found that key is distinguishing between the speed of an individual electron and the speed of the electric field that pushes it. Think of a long pipe already completely full of marbles; if you push one marble in one end, another one pops out the other end almost instantly. The "push" traveled through the pipe very fast, but each individual marble only moved a tiny distance. A wire is the same: it's already packed with electrons. When you apply voltage, the electric field (the "push") propagates at nearly the speed of light, telling all the electrons to start moving at once. This slow, collective movement is the drift velocity you read about. Your lamp lights up instantly because the electrons already in the filament get that near-light-speed "push" and start moving, not because an electron had to travel all the way from the battery.
Tyler Arbogast
2025-10-12 02:35:24 +0000 UTCThis may not fit this video, but Dave I hear you mentioned electron “drift velocity”. I read in an electronic textbook that it is .002 mm per second with a 1.5 volt battery hooked to a small lamp using 15 awg copper wire. What the heck, I have always thought electrons zipped around at a fraction of light speed. Maybe just a dumb assumption I guess. Can someone explain what is going on here.? Thank you.
Billy Martin
2025-09-30 12:56:15 +0000 UTC
