## Electrical Engineering: Principles & Applications (6th Edition)

$P_I=-120W$ $P_V=120W$
We use the equation for power to find: $$P_I = -VI \\ P_I = -(10A)(12V) \\ P_I = \fbox{-120W}$$ We use the equation for power again. In this case, however, there is no negative sign, for the current goes from higher (the positive) to lower (the negative) potential, meaning that the battery is being charged: $$P_V = VI \\ P_V = (10A)(12V) \\ P_V = \fbox{120W}$$ Note, in the case of the current generator, the power is negative, so energy is given off, but in the case of the resistor, the power is positive, so energy is taken in.