A coil has resistance 30 ohm and inductive reactance 20 ohm at 50 Hz frequency. If an ac source, of 200 volt, 100 Hz, is connected across the coil, the current in the coil will be

Options

(a) 4.0 A
(b) 8.0 A
(c) 20 / √13 A
(d) 2.0 A

Correct Answer:

4.0 A

Explanation:

If ? = 50 x 2π then ?L = 20Ω
If ?’ = 100 x 2π then ?’L = 40Ω
I = 200 / Z = 200 / √ R² + (?’L)²
= 200 / √ (30)² + (40)²
I = 4 A