Ask A Scientist© Physics Archive

Question:  Exactly how fast do electrons travel?
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Answer:  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