In an a.c. circuit, the instantaneous e.m.f. and current are given by i = 20 ( 30t -…

PHYSICS · Single correct · A Level · Physics · Fields and their consequences · Fields and their consequences

Problem

In an a.c. circuit, the instantaneous e.m.f. and current are given by

e = 100 \sin 30t

i = 20 \sin \left( 30t - \frac{\pi}{4} \right)

In one cycle of a.c., the average power consumed by the circuit and the wattless current are, respectively: (1) 50W, 10A (2)

\frac{1000}{\sqrt{2}}

W, 10A (3)

\frac{50}{\sqrt{2}}

W, 0 (4) 50W, 0