Question

A coil has inductive reactance \(3\) H. The ratio of its reactance when it is first connected to an a.c. source and then to d.c. source is

• A. zero
• B. \(3\)
• C. infinite
• D. \(1.5\)

Hint:

For d.c., the frequency is zero, so X_L = 0.

Answer 1

The Correct Option is C

Step 1: Idea:
An inductor opposes only a changing current.

Step 2: D.C.:
A steady current has no change, so it meets zero inductive reactance.

Step 3: Ratio:
Non-zero divided by zero is infinite. Option (C).

Final Answer:
Inductive reactance vanishes for d.c. \[ \boxed{C} \]