Why is the average thermal velocity 0?

Question

Thermal velocity is the velocity of the free electron due to their random motion. So how is the average value 0?

why should a free electron be more likely to be moving left than right? — By Symmetry, May 14 '16 at 15:43
@BySymmetry I love how your username perfectly fits your comment :-P — AccidentalFourierTransform, May 14 '16 at 15:46
Gupta ji , If it was not 0, your object will run out of electrons. — Anubhav Goel, May 14 '16 at 15:57
I think you are confusing the average velocity (i.e., first velocity moments) with the thermal speed (i.e., can be from the second velocity moment with some assumptions). — honeste_vivere, May 22 '16 at 18:07

score 2 · Accepted Answer · answered May 14 '16 at 15:48

2

Their average speed would be non zero but their average velocity would be zero as long as they are not moving preferentially in one direction.

answered May 14 '16 at 15:48

M. Enns

1 Answers1