# Electric Potential

1. Feb 3, 2010

### collegeconfid

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.

2. Feb 3, 2010

### collegeconfid

If the values for the potential difference and kinetic energy seem irregular, it was because I made them up, realizing that they were not relevant to my question.
any help would be much appreciated.

3. Feb 3, 2010

### Redbelly98

Staff Emeritus
It's sounds like they are not specifying whether the ion goes through an increase or a drop in voltage, just that the voltage changes by 10V. As such, they are probably just concerned with the magnitude of the charge, and not whether it is positive or negative.

You are correct that, if the kinetic energy increases when moving to a +10V higher voltage, then it must have a negative charge.