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Hi everyone,

1. Homework Statement

Hi everyone,

1. Homework Statement

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?

## Homework Equations

-We/q = ΔV

C = Q/V

## 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..