NCERT · Class 12 · Physics · Alternating CurrentWhat is Wattless Current? Under what condition does it flow in an AC circuit?

Wattless current is defined as that electric current flowing in an AC circuit for which the average power consumed over a complete cycle is zero. This situation arises in a purely inductive or purely capacitive circuit where the phase difference between the voltage and the current is $\pi/2$ or $90^\circ$. The component of current $I_{rms} \sin \phi$ which is perpendicular to the voltage is responsible for this effect. Since power consumed $P = V_{rms} I_{rms} \cos(90^\circ) = 0$, no electrical energy is dissipated as heat.