1. The problem statement, all variables and given/known data A proton moves in a constant electric field E from point A to point B. the magnitude of the electric field is 6.4x10^4 N/C. The direction of electric field is opposite to the motion of the proton. If the distance from point A to point B is 0.50m, what is the change in the proton's electric potential energy, EPEb-EPEa? E=6.4x10^4 N/C Δd= 0.50 ΔV=? 2. Relevant equations ΔV=Δd*E V=W/q W=qEcosθ 3. The attempt at a solution ΔV=Δd*E=(6.4x10^4)(0.50) = 32000J Clearly this is wrong, as the answer is supposed to be 5.1x10^-15J. Apparently you need to multiply it by the proton's charge, 1.602x10^-19C, and you would get the answer. but why? i dont see any formulas that would suggest me to multiply my answer by the fundamental charge.