A. 100Ω
B. 200Ω
C. 300Ω
D. 500Ω
Correct Answer:
Option B = 200Ω
Explanation
Power of the lamp = 60W;
I=P/V
I=60/120
= 0.5A
R=V/I
Rmains = 220/0.5 = 440Ω
Rlamp = 120/0.5 = 240Ω
∴ The non-inductive resistance to keep the lamp = (440−240)Ω
= 200Ω