Question

Q:The instantaneous magnitude of voltage and current in an AC circuit is 5sin(wt+30°), 6cos(wt-60°) respectively. The circuit operates at? (A) unity power factor (B) zero power factor leading

(C) zero power factor lagging

(D) none of these

Answer 1

Answer:

(A) Unity power factor

Explanation:

Current given by $6cos(\omega t-60^0)$ can be written as:-

$I=6cos(60^0-\omega t)\\\\=>I=6sin(90^0-60^0+\omega t)\\\\=>\boxed{I=6sin(30^0+\omega t)}$

Since this expression is at 0 phase difference w.r.t voltage, V and I are in phase, i.e $\boxed{\phi =0}$

Therefore

Power factor = $cos(\phi)$

Power factor = 1

Hope this answer helped you :)