which one of the following statements concerning an ac circuit is true?

Question

a) when only resistance is present in an ac circuit, voltage and current are in phase.
b) on average, the power dissipated by resistor in an ac circuit is zero.
c) for a resistor in an ac cicuit, the current and voltage are 90 degree out of phase.
d) the current and voltage are in phase for a capacitor in an ac circuit.
e) inductors in an ac circuit offer little opposition to current at high frequencies.

Answer 1

a is true, always.