# Electron question

1. Aug 16, 2004

### Physics_Student

Simple question;

For an electron, what is its velocity after it has been accelerated through 50V?

I thought about equating 50eV to KE, but I know thats the wrong way, any ideas?

Nav

2. Aug 16, 2004

### vanesch

Staff Emeritus
Why is that wrong ??

cheers,
Patrick.

3. Aug 16, 2004

### Physics_Student

dunno, it doesnt feel right? is that way the correct way?

4. Aug 16, 2004

### cepheid

Staff Emeritus
It's correct because an electron volt is defined as the energy gained by an electron (elementary charge) when accelerated through a potential difference of 1 V. So 50V imparts 50eV to the electron, which is equal to its final kinetic energy. From that you can easily calculate it's final velocity.

5. Aug 16, 2004

### Gonzolo

Don't forget to consider initial energy, velocity, direction etc.

6. Aug 17, 2004

abd dont forget to calculate that using relativistic Kinetic Energy.

7. Aug 17, 2004

### zefram_c

I don't think that's needed here; the electron's rest mass is about 0.5MeV and we're talking a KE of 50eV.