1. The problem statement, all variables and given/known data The work done by an external force to move a -8.0μC charge from point a to point b is 8.0 × 10-3J. If the charge initially at rest had 4.0 × 10-3J of kinetic energy ab point b, calculate the potential difference between a and b. 2. Relevant equations V = W / q 3. The attempt at a solution Work done per unit charge to move a positive charge from a to b is V = W / q = 8.0 × 10-3 / -8.0 × 10-6 = -1.0 × 103V At a Ek is 0J and at b it is 4.0 × 10-3J, so ΔEk = 4.0 × 10-3J. So work done for each electron to give Ek is V = W / q = 4.0 × 10-3 / -8.0 × 10-6 = -0.5 × 103V Having Ek means that energy is not dissipated. P.d. is the power dissipated per unit current so (-1.0 × 103) - (-0.5 × 103) = -0.5 × 103V Is it right way to do it? Do I need to get rid of negative sign when I calculate the p.d.?