Question

Obtain an expression for the power in a.c. circuit containing a resistance and capacitance in series.

Answer 1

Average power in CR-circuit

Let alternating e.m.f. applied to CR circuit be

E = E₀ sin ωt

Let alternating current developed, leads the applied e.m.f. by Φ then

I = I₀ sin (ωt + Φ)

∴ Instantaneous power,