Question

If a current $I$ given by $I_0\sin (\omega t-\pi /2)$ flows in an AC circuit across which an AC potential of $E_0\sin \omega t$ has been applied, then the power consumption $P$ in the circuit will be:

• A. $E_0{I}_0/\sqrt{2}$
• B. $E_0{I}_0/2$
• C. $EI/\sqrt{2}$
• D. zero

Answer 1

The correct option is D zero

$I=I_0(\sin \omega t-\frac{\pi }{2})E=E_0\sin \omega t$

Here E and I are in out of phase $[\theta =\frac{\pi }{2}]$

$\therefore$ Power factor $\cos \theta =\cos 90=0$

$\therefore$ Power consumption become zero.