# If eV=pV than

1. Nov 28, 2008

### u2_wa

Suppose scientists had chosen to measure small energies in proton volts rather than electron volts. What difference would this make?

Last edited: Nov 28, 2008
2. Nov 28, 2008

### cepheid

Staff Emeritus
Doesn't the proton have the same charge as the electron? It's really late and I'm tired and can't think, but I'm clinging to that statement because I can't imagine how else hydrogen would be neutral. So that means the charge of the proton is just +e, whereas the electron is -e. Incidentally, the electron volt (and the proton volt, I guess) are units of energy, not charge. So your original question doesn't make sense. Scientists don't measure charge in electron volts in the first place.

The electron volt is the amount by which the energy of a particle with charge of magnitude e would change as it moved through a potential difference of one volt. The only difference between the two is that the electron would lose energy and the proton would gain energy (if the potential difference were positive i.e. if the electric potential *increased* by one volt between the starting and final positions of the charge). Vice versa if the potential difference were negative. Again, it's late, and I may have the signs wrong. You figure it out. Either way, it's irrelevant because we're just considering the *amount* by which the energy changed and using that as a unit of energy.

3. Nov 28, 2008

### Staff: Mentor

Yes, a "proton volt" would be the same as an "electron volt," as a unit of energy, because the magnitude of the charge is the same on the two particles.

4. Nov 28, 2008

### Redbelly98

Staff Emeritus
I'll assert that we really do use protonvolts in practice, since we use (+e) times (+1v) for this unit of energy. We just call it an electronvolt.

5. Nov 28, 2008

### cepheid

Staff Emeritus
Good call...(IMO), as far as nomenclature is concerned.

6. Nov 28, 2008

### Redbelly98

Staff Emeritus
Of course, one could also argue we are using positronvolts