Question

In the circuit given below, the series circuit shown in figure, for series resonance, the value of the coupling coefficient, K will be?

(a) 0.25

(b) 0.5

(c) 0.1

(d) 1

Answer 1

Right choice is (a) 0.25

Explanation: Mutual inductance wm = ω k \(\sqrt{L_1 L_2}\)

Or, m = \(k.2.8 j^2\)

= 4k.j

At resonance, Z = 20 – j10 + j2 + j6 + 2.4kj – 2j + 8kj = 0

Or, -2 = -8k

Or, k = \(\frac{1}{4}\) = 0.25.