Question

what do you mean by power factor of an ac circuit

Answer 1

Power Factor is an AC circuit is defined as the ratio of the real power to that of the apparent power.

Another interpretation of power factor would be that it is the percentage of maximum power that can be offered by a given circuit if it operated under resonance conditions.

Now,

for a purely inductive and capacitive circuits, power factor = 0

for a purely resistive circuit, power factor = 1

and

for an LCR circuit the values of power factor could lie between 0 and 1.