1. Three point charges +Q1, -Q2, +Q3 are equally spaced along a line. If the
magnitude of Q1 and Q2 are equal, what must be the magnitude of Q3 in order
that the net force on Q1 be zero.
2. Find the force and electric field on a point charge of 2 Q coulomb at the center of the square 20cm on one side if four identical point charges of Q coulomb are located at the corners of the square.
