# Electron Charge

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1. Jul 28, 2016

### DjLeo

My question is, Why do we use q=1.6*10^-19 C rather than -1.6*10^-19 C, for the charge on an electron in most of the equations?

2. Jul 28, 2016

### Staff: Mentor

Hi DjLeo.

As for your question...I don't believe we do, actually. But let me move this over to General Physics and the people there will sort you out.

3. Jul 28, 2016

### Staff: Mentor

It is a complete and total historical accident. As early as the 18th century, long before the discovery of the electron or any other subatomic particle, it was known that there were two types of charge, and that like repelled and unlike attracted. The choice of which we would call negative and which we would call positive was completely arbitrary.

Many years later the electron was discovered, and it turned out that it had the kind of charge that we had been calling negative: https://xkcd.com/567/

4. Jul 28, 2016

### Khashishi

It's completely arbitrary whether you say the charge on an electron is -q, with q=1.6*10^-19C, or +q, with q=-1.6*10^-19C