Question

workdone by electric field or external agent

Answer 1

What about it?

Answer 2

explain

Answer 3

what is it please explain it

Answer 4

The work done by any force to move a point +ve charge from a to b is given by \[W = \int\limits_{a}^{b}F.dr\] F.dr = |F||dr|cos(a) where a is the angle between applied force and displacement produced. Since the work done by an external agent will obviously be due to a force in the direction of the displacement cos(a) =1. Similarly it will be -1 for electric field as it will act against the produced displacement.
since work done is a vector this shown by
W(E) = - W(Agent).