Post by 1dave on Apr 5, 2020 21:56:17 GMT -5
Questions and Answers - How fast do electrons move?
You may wonder how fast the electrons are whizzing around in the atoms around you. A good example (and the most simple to calculate) is the hydrogen atom which is in all our water.
A calculation shows that the electron is traveling at about 2,200 kilometers per second. That's less than 1% of the speed of light, but it's fast enough to get it around the Earth in just over 18 seconds.
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 electrons 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).
Although the drift velocity in a wire is small, the thermal velocity of the electrons tends to be quite large. Something of the order of 100,000 meters/sec. So they are buzzing about at random at high speeds, with a small superimposed drift velocity caused by the electric field.