Consider a charge of +2.0 µC placed at the origin of an X-Y co-ordinate system and a charge of -4.0 µC placed 40.0 cm to the right. Where must a third charge be placed – between the charges, to the left of the origin, or beyond the second charge – to experience a net force of zero? Argue your case qualitatively without working out a solution. Consider both positive and negative charges.
The Attempt at a Solution
Wouldn't you have to place the third one directly in the middle of the two charges? because you will then have the left side of the third one being positive and the right side of the third one being negative, therefore canceling out to zero, and the opposite would apply for a negative third charge...
But i'm not sure that i am correct with my reasoning...