# Where the total electric field is equal to zero?

by barrett
Tags: electric, equal, field
 P: 2 1. The problem statement, all variables and given/known data Two point charges of -2.5 µC and 6.0 µC lying along the x axis are 1.0 m apart. Locate the point (other than infinity) at which the total electric field is zero. 2. Relevant equations I was thinking: E=F/q and F=K (Q x q)/d^2 But I'm not quite sure how to use them. 3. The attempt at a solution Using the second equation I found F to be -.135. But I don't think that's right, and then when plugging that into the E=F/q. E would have to be zero, since I'm trying to find where the total electric field is zero? Then there's no solutions other than infinity, are there? And what exactly is q in the first equation. I really have no idea what's going on here.
 P: 778 If the electric field is zero, is it the case that the force is also zero? So find the point(s) where the net electric force or field is zero.
 P: 2 I found an example online and I think I substituted the right numbers in for this problem, is this how it would be solved? (I didn't understand the equation below and where it came from: KQ/x²-2.4KQ/(x+1.00)²) Enet=Esub1 + Esub2 = KQ/x²-2.4KQ/(x+1.00)² KQ/x²-2.4KQ/(x+1.00)² The Ks and Qs cancel out leaving: 1/x² = 2.4/(x+1.00)² And then get it into a quadratic: 1.4x² - 2x -1=0 And find it to be 1.82 m to the left of charge Q. I ignored the other root, -.39m because that would be between the two charges where the fields cannot cancel out. Am I on the right track?

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