Four equal point charges, Q, are fixed at the corners of a squareof side b. (a) What is their total electrostatic potential energy?(b) How much potential energy will a fifth charge, Q, have at thecenter of the square (relative to V=0 at r =)? (c) If constrained to remain in that plane, is the fifth charge in stable or unstable equilibrium? (d)If a negative (-Q) charge is at the center, is it in stableequilibrium?