Magnitude of the work done by electric field.

[jlmccart03]

Homework Statement

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?

Homework Equations

W = F*d
W = V*U

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.

 

[mfb]

Just a multiplication error.
Quick check: If you multiply 1.6*10^-19 by 0.072, the result should be smaller than 10^-19.

 

[jlmccart03]

Just a multiplication error.
Quick check: If you multiply 1.6*10^-19 by 0.072, the result should be smaller than 10^-19.

Yeah I keep getting 1.15e^-19. Isn't that correct, I can't seem to get a different answer on my calculator. Nevermind I got the answer. I was using -18 instead of -19.