The potential difference between two points is the work done moving a unit positive charge from one point to another point. If the potential at point A is V_A and the potential at point B is V_B, then the potential difference (Δ V):

Δ V = V_B - V_A ……………………………….. (3-5)

Therefore, the potential difference is the potential energy per unit charge:

Δ V = W/q …………………………………… (3-6)

Where Δ V = potential difference

W = potential energy

q = charge