# Electrical potential problem

1. Mar 27, 2014

### Latsabb

The problem is to find the potential at a point that is 3 meters away from two charges. (one 3 meters above, and the other 3 meters below)

q1=3μC
q2=6μC

I put that Ep=Epq1+Epq2

Epq1=K*q1/r1
Epq2=K*q2/r2

K=1/(4πε0)=8.988x109

This gives me:

Epq1=8.988x109*(3x10-6/3)=8988J

Which immediately set some bells off for me. Isnt that quite a bit of energy for a charge three meters away? By the same formula, Epq2 equals 17976J, for a total potential of 26964J. Maybe I am wrong, but it seems like a very high potential. I will admit that I havent wrapped my head around how large of charge a Coulomb is, so maybe 3μC and 6μC are very large amounts of charge, but something seems wrong to me...

Can someone take a look, and see if I did something wrong? Thank you.

2. Mar 27, 2014

### TSny

Hello, Latsabb.

Note that you are calculating potential, not potential energy. The unit of potential is not J.

A μC is a large amount of charge for a particle. So, a large value of potential in this problem is to be expected.

3. Mar 27, 2014

### Latsabb

Ok, thank you. Being that I am not calculating potential energy, that would make this... Volts? So I should be replacing my Ep's with V?

4. Mar 27, 2014

### TSny

Yes. So, you are getting some "high" voltages because your charges are on the order of a few μC and your distances are on the order of a few meters.