Can Instantaneous Power Output Of Ac Source Ever Be Negative

Can the instantaneous power output of an AC source ever be negative? Can the average power output be negative?

Answers:

Key concept: Power in ac circuits: In dc circuits power is given by P = Vi.
But in ac circuits, since there is some phase angle between voltage and current, therefore power is defined as the product of voltage and that component of the current which is in phase with the voltage.