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Question:
Exactly how fast do electrons travel?



Replies:
Electrons can have a wide range of speeds. A slow case: we know that electrons move when there is a current flow in a wire, but the speed at which the electrons themselves move in the wire -- the so-called electron drift velocity -- surprises most people. For example, for a copper wire of radius 1 mm carrying a steady current of 10 amps, the drift velocity is only about 0.024 cm/sec ! On the fast side: the Bohr model of the hydrogen atom has the (bound) electron zipping around the nucleus at about 2 million meters/sec. And on the very fast side, some examples are: beta particles, which are emitted by some radioactive materials; and the innermost elec- trons of atoms of elements having large atomic number, such as uranium. In these cases the electrons are traveling at very nearly the speed of light. (about 300 million meters/sec).

Rcwinther



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