# Velocity of atomic (hydrogen) electrons

## Main Question or Discussion Point

Hello,

I've been wondering about the velocity of hydrogen electrons. I've read that 242,000 m/s was the correct velocity, however, I thought electrons would travel at c. How does one calculate this number?

## Answers and Replies

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malawi_glenn
Homework Helper
Why would/should electrons travel at c?

One can measure/calculate the mean momentum & kinetic energy of the atomic electron, then it is trival to obtain its velocity.

pam
mv^2=27 eV, so $$v/c=\sqrt{27/500,000}$$

Can you explain that equation, if you get a chance? Why does mv^2=27ev
Thanks.