Hi everyone, 1. The problem statement, all variables and given/known data It takes 18 J of energy to move a 0.30-mC charge from one plate of a capacitor to the other. How much charge is on each plate? 2. Relevant equations -We/q = ΔV C = Q/V 3. The attempt at a solution -18J/0.3.10-3 C * 15.10-6 F = Q Q = -0.9 C The problem is that in the book, the answer is 0.9 C but i found -0.9C. I had many problems with the formula -We/q = ΔV sometimes in the book they let the negative sign and sometimes not. If someone can explain me that..