Page 354 - Basic Electrical Engineering

Power factor,

cos ϕ = cos 30°

= 0.866 lagging

Impedance,

In rectangular form,

Z = 10(cos 30° + j sin 30°)

= 10 × 0.866 + j 10 × 0.5
= 8.66 + j5.0

= R + jX L

R = 8.66 Ω

and X = 5.0 Ω
L
Again XL = ωL = 314 L

= 15.92 mH

Example 3.19 The expression of applied voltage and current flowing

through an ac series L–R circuit are

Calculate for the circuit (i) power factor; (ii) average power; (iii) impedance;
(iv) R and L