Positive and negative point charges of equal magnitude are kept at (0,0,a/2) and (0,0,−a/2) respectively. The work done by the electric field when another positive point charge is moved from (−a,0,0) to (0,a,0) is −a/2) respectively. The work done by the electric field when another positive point charge is moved from (−a 0) is 0) [...]