# Work done by moving a charge

1. Aug 12, 2009

### heynkm1

1.

If the electrical potential across a conducting metal rod of length L is V, how much work is done in moving a charge of +ne across the length of the rod, from low to high potential?

2.

Equation that I used: delta U = q * V

3.

This is what I thought: the charge moves from low to high potential, so the work done (by the electric field) has to be negative (so W = -neV). The answer was W = +neV.

Is my thought process incorrect, or should the question have been more specific and ask for exactly the work it was looking for (Work done by electric field or work done by external force)?

2. Aug 12, 2009

### RoryP

Hi welcome to PF!

Think about what units the eqaution WD=V*q would have then look at the answer you gave us :D

3. Aug 12, 2009

### Staff: Mentor

The presumption (tacit, unfortunately) of the question is: What work would need to be done by you (an external force) to move the charge (not the work done by the field, when the charge is moved).

4. Aug 12, 2009

### heynkm1

OK, thank you for your help.