1. The problem statement, all variables and given/known data The membrane around a cell normally has layers of charge that create a potential difference between its outer and inner surfaces. This difference is about 72 mV . When a singly ionized potassium ion moves through a channel in the membrane passing from the outside to the inside, what is the magnitude of the work done by the electric field of the membrane? 2. Relevant equations W = F*d W = V*U 3. The attempt at a solution So I know that the charge of a K ion is +1 so it is simply 1.6e-19 and converting 72 mV to 0.072 V I can then just multiply both to get the change in work correct? I don't get why that is wrong then.