Question

The electrostatic work done on a particle carrying charge q as the particle travels from point A to point B in an electric field is W.

How much electrostatic work is done on a particle carrying charge -2q that travels from B to A in the field? Express in terms of W

Answer 1

Since we can relate work from A to B as

$$W=\phi q,$$

where ϕ is the potential of the field where a charge is placed, the work in the opposite direction is -W, while the doubling the charge gives $-2W.$