Question

A resistance of 40 ohm and an inductance of 95.5 millihenry are connected in series in a 50 cycles/second ac circuit. The impedance of this combination is very nearly

• A. 30 ohm
• B. 40ohm
• C. 50 ohm
• D. 60 ohm

Answer 1

Answer: (C)

50 ohm

Answer 2

$X_{L} = 2\pi\nu L = 2 \times 3.14 \times 50 \times 95.5 \times 10^{- 3} = 29.98\Omega \approx 30\Omega$Impedance $Z = \sqrt{R^{2} + X_{L}^{2}} = \sqrt{(40)^{2} + (30)^{2}} = 50\Omega$