Physical Effects of Electricity
A 22-gauge metal wire three feet in length contains approximately 28.96 ×1021 “free” electrons within its volume. Suppose this wire is placed in an electric circuit conducting a current equal to 6.25 ×1018 electrons per second. That is, if you were able to choose a spot along the length of this wire and were able to count electrons as they drifted by that spot, you would tally 6,250,000,000,000,000,000 electrons passing by each second. (This is a reasonable rate for electric current in a wire of this size.)
Calculate the average velocity of electrons through this wire.
In the late 1700’s, an Italian professor of anatomy, Luigi Galvani, discovered that the leg muscles of a recently deceased frog could be made to twitch when subjected to an electric current. What phenomenon is suggested by Galvani’s discovery? In other words, what does this tell us about the operation of muscle fibers in living creatures? More importantly, what practical importance does this have for people working near electric circuits?
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