1. The problem statement, all variables and given/known data An ion accelerated through a potential difference of 10V experiences an increase in kinetic energy of 7 J. Calculate the charge on the ion. 2. Relevant equations U=qV -qV=W 3. The attempt at a solution My book says the charge is positive, but I think that the charge is suppose to be negative. Did the book make a mistake or am I missing something? Whether the charge is positive or negative does matter right? Thanks for any help.