What is the Default Speed of an Electron in a Vacuum?

[physx_420]

This isn't a homework question but if it belongs in another thread please tell me so I can switch it.

I was just wondering if there is an "agreed-upon" speed that an electron would travel in say a vacuum? I understand that one can continue adding energy until the electron reaches very nearly the speed of light, but how fast does it go to begin with? Sorry in advanced if this is somewhat trivial.

 

[Dr Lots-o'watts]

A speed relative to what?

 

[tiny-tim]

hi physx_420!

an electron can have zero speed

as Dr Lots-o'watts says, its speed depends on the frame of the observer

 

[Bob S]

A group at the University of Washington had a single electron stored in a magnetic trap (in vacuum) for about 6 months, but one morning they looked for it and it wasn't there. How fast is that?

CERN in Switzerland built an accelerator that accelerated electrons to about 50 billion electron volts (in vacuum), which is about 0.999999999 times the speed of light.

Bob S

 

[mrspeedybob]

hi physx_420!

an electron can have zero speed

Can it really? Electrons, like everything else, are subject to the Heisenberg uncertainty principle. If it's velocity is zero then it's position would be infinitely uncertain, it would have an equal probability of being anywhere in an infinite universe. I don't believe the universe is infinite to its velocity cannot be zero. It can be uncertain within a range that includes zero, but that is a different thing.

 

[K^2]

The expectation value for velocity can nonetheless be zero.

 

[HallsofIvy]

Light is the only thing that has a fixed speed relative to all reference frames so, as others said, the question doesn't make sense. There is NO one speed all electrons must have.