posted by Lisa .
Help, I know the answer is 4.8 X 10^-19, but I can not figure out how to do it or what formula to use. The question is "A charge moves a distance of 1.7 cm in the direction of a uniform electric field whose magnitude is 220 N/C. As the charge moves, its electrical potential energy decreases by 1.8 x 10^-18 J. Find the charge on the moving particle. Thanks.