а. Define electric pоtentiаl аnd equipоtential surface. Explain the prоperties of equipotential surfaces. (4 pts) b. The figure shows a thin plastic rod of length L = 11.4 cm and uniform positive charge Q = 52.7 fC lying on an x axis. With V = 0 at infinity, find the electric potential at point P1 on the axis, at distance d = 2.40 cm from one end of the rod. (6 pts)