Electric field strength,
E= 1600 N/C.
AB: No work as they are along equipotential lines.
AC is the same as BC as E= V/d , V = Ed
Work = q (Ed)= (1uC)(1600x0.08m) = 128 J
The work is independent of the path whether A to C or B to C.
A positive charge moving form A/B to C would work done against electric force. A negative charge moving from A/B to C would have work done on it by electric force. The positive charge would have increase in EPE = 128J .
A negative 1uC moving from the same locations would have decrease in EPE = 128J .
