A charge of #4 C# is passing through points A and B on a circuit. If the charge's electric potential changes from #19 J# to #7 J#, what is the voltage between points A and B?
If you move 1C of charge through a potential difference of 1V then 1J of work is done.
The amount of work done here is 19 - 7 = 12J
So 4C would require a p.d of 3V to do 4 x 3 = 12J of work
Or using dimensions:
The question should read potential energy, not potential which is in volts not Joules.