Question

Two identical point charge Q are kept at a distance r from each other. A third point charge q is placed on the line joining the above two charges such that all the three charges are in equilibrium. What is the magnitude, sign and the position of the third charge ?

Answer 1

since the q charge in equilibrium then it must that its posiition is at r/2 if both Q charge have + sign and q charge have - sign
or
if both Q charges have -ve sign and q have +ve sign