# Homework Help: Electric field/ potentials

1. Feb 10, 2005

### linemanpete

ok i've "hit the wall" on this question and im wondering if someone could help me

a +charge q1 is located 3.00m left of a -charge q2. the charges are not equal in magnitude. There is 2 spots on a line through the charges where the potential is 0. 1 spot on this line where the electric field is 0 is 1m to the right of q2. What are the 2 spots of 0 potential relative to the negative charge?

I realize that q1>q2 (magnitude) since the Electric field components cancel eachother out to the right of q2
but from there im very stuck

thanks

2. Feb 10, 2005

### StatusX

Zero potential is not the same as zero field. Just find the total potential by adding the potential from each charge, plug in the first zero to get an equation relating q1 and q2, plug in for q2, and then solve for the second zero. You shouldn't need to know q1 to get the second zero, since you should be able to factor it out front. Also, don't forget the potential depends on the absolute value of the difference in position, or you'll only be able to find one zero.

Last edited: Feb 10, 2005