In an a.c circuit the e.m.f. (e) and the current (i) at any instant are given respectively by
e = E₀ sin ?t
i = I₀ sin (?t – ?)
The average power in the circuit over one cycle of a.c. is

Options

(a) E₀I₀ / 2
(b) E₀I₀ / 2 sin ?
(c) E₀I₀ / 2 cos ?
(d) E₀I₀

Correct Answer:

E₀I₀ / 2 cos ?

Explanation:

The average power in the circuit over one cycle of a.c. is given by
Pₐᵥ = eᵣₘₛ x iᵣₘₛ x cos ?
= E₀ / √2 x I₀ / √2 x cos ? = E₀I₀ / 2 cos ?