Apoint charge q is held fixed in place and another point charge q is brought closer to it moving at constant velocity. which of the following statement(s) is (are) true?
i. the electrostatic potential energy of q increases as it is brought closer to q if q and q are of the same sign.
ii. the work done by the electrostatic force is positive if q and q are of the same sign.
iii. the work done by an external force to bring q closer to q is positive if q and q are of the opposite sign.
iv. the work done by an external force to bring q closer to q is negative if q and q are of the opposite sign.