Conversion units mystery. Am I wrong?

[giraffeinaboat]

Homework Statement

The potential difference between two points is 140mV. If 280μJ of work are required to move a charge Q from one point to the other, what is Q?

Homework Equations

Q = W/V

The Attempt at a Solution

http://imgur.com/FDaQfb9

 

[ehild]

Hi, welcome to PF!

Convert the potential difference to volts, and the work to joules. Dividing joules with volts, you get coulombs for the charge. mJ/mV is also coulomb.

ehild

 

[voko]

You are assuming that mJ divided by mV gives mC. That's wrong, it gives C. In general, you have overcomplicated things too much. Just convert everything into J and C, compute the result, then convert it to any units you want.