Question

In the circuit given below, the input impedance ZIN of the circuit is _________

(a) 0.52 – j4.30 Ω

(b) 0.52 + j15.70 Ω

(c) 64.73 + j17.77 Ω

(d) 0.3 – j33.66 Ω

The question was posed to me in quiz.

My doubt stems from Dot Convention in Magnetically Coupled Circuits topic in chapter Resonance & Magnetically Coupled Circuit of Network Theory

Answer 1

Correct choice is (c) 64.73 + j17.77 Ω

The best I can explain: ZIN = (-6j) || (ZA)

ZA = j10 + \(\frac{12^2}{(j30+j6-j2+4)}\)

= 0.49 + j5.82

ZIN = \(\frac{(-j6)(0.49+j5.82)}{(-j6+0.49+j5.82)}\)

= 64.73 + j17.77 Ω.