Vb - Va = -366.7 V.
Vab = Va - Vb, the potential of a with respect to b, is equal to the work done by the electric force when a unit of charge moves from a to b, it is given by:
Vab = Va - Vb = Wab/q,
So, in order to determinate the potential difference Vb - Va we have to multiply by -1 both side of the equation above:
- (Va - Vb) = - (Wab/q)
Resulting
Vb - Va = -(Wab/q)
Given a positive charge q = 6.0μC = 6.0x10⁻⁶C, Wab = 2.2x10⁻³J. Determine Vb - Va.
Vb - Va = - (2.2x10⁻³J/6.0x10⁻⁶C)
Vb - Va = -366.7 J/C = -366.7 V