Problem 7: If 280 J of work is done in carrying a charge of 2 C from a place where the potential is -12 V to another place where potential is V. Calculate the value of V.
We know that potential at a certain point is the work done in moving a unit charge to the point. Therefore, we calculate the change in potential. Potential at first point is
280/2 = 140 volts.
If V (as given) is the potential at point B, then, ΔV = V-(-12) =V+12. Substitute this value,
V + 12 = 140 ⇒ V = 128 volts (Answer)