Cracking the SAT Physics Subject Test

4. How much work is done by the electric field as a charge moves
   along an equipotential surface?

Here’s How to Crack It

If the charge always remains on a single equipotential, then the potential, V, never
changes. Therefore, ∆V = 0, so ∆UE = 0. Since WE = −∆UE , the work done by the

electric field is zero.