# Electric Potential Question

## Homework Statement

My question is one of clarification about electric potential.

See Below

## The Attempt at a Solution

I understand that when electric potential is defined at infinity to be zero for a series of point charges, the potential is simply kq/r. My question is is it possible to define zero to be at the origin, and if so what would the new expression be. It would seem that the integral would yield a 1/0 term which would be undefined.

collinsmark
Homework Helper
Gold Member
Yes, you can define the potential to be 0 at any place you want, assuming that there is not a point charge at that particular location.

Electric potential always assumes potential difference, meaning that the potential at one point is always in reference to some other point.

Assigning 0 Volts at infinity (meaning infinity is the reference potential) is merely a convention, not a hard and fast rule.

If you choose some other place besides infinity as the 0 potential, you might get different numerical answers to the particular problem than the answers your textbook gives. But it's still valid for you to do that for your own purposes, as long as you are self consistent.

But as you've implied, don't define the reference potential at the very location where a point charge resides. You'll get a nonsensical answer.

But that's really no different from the situation where you define infinity as the location of 0 V and then try to find the potential at the very location where a point charge resides. In that situation you'll also get a nonsensical answer.