ความคิดเห็นที่ 14
http://www.newton.dep.anl.gov/askasci/phy99/phy99092.htm
NEWTON is an electronic community for Science, Math, and Computer Science K-12 Educators.
Argonne National Laboratory, Division of Educational Programs, Harold Myron, Ph. D., Division Director.
speed of electrons
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 veryfast 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
จากคุณ :
j (สิงห์สาโท) 
- [
6 ก.ค. 51 12:54:48
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