Question

You are given two unknown point charges, Q, and Q. At a point on the line joining them, one third of the way from Q1 to Q2 the electric field is zero. What can you say about these two charges?

Answer 1

* You are given two unknown point charges, Q1 and Q2...

Answer 2

Recall the electric field at any point is the sum of the fields for both charges, and is proportional to q/r^2. You can solve for a charge proportionality with this by setting the two equal. Also, if the charges are opposite, the two fields would add to each other. This leads to the conclusion that the two charges must be...