Question

The average power lost in pure capacitor in an $A.C$. circuit:

• A. is zero
• B. depends on V
• C. depends on C
• D. depends on insulator placed in parallel plate capacitor

Answer 1

Answer: (A)

Average power of A.C. circuit
$P_{a v}=V_{ \text{rms }} \times I_{\text{rms }} \cos \phi$
If circuit contains only capacitor, then
$\phi =-\frac{\pi}{2}$
$\therefore \cos \phi =\cos \left(-\frac{\pi}{2}\right)=0 $
so, $ P_{a v} =0$