Question

Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): Choke coil is simply a coil having a large inductance but a small resistance. Choke coils are used with fluorescent mercury-tube fittings. If household electric power is directly connected to a mercury tube, the tube will be damaged.
Reason (R): By using the choke coil, the voltage across the tube is reduced by a factor \( \frac{R}{\sqrt{R^2 + \omega^2 L^2}} \), where \( \omega \) is the frequency of the supply across resistor \( R \) and inductor \( L \). If the choke coil were not used, the voltage across the resistor would be the same as the applied voltage.
In light of the above statements, choose the most appropriate answer from the options given below:

• A. Both (A) and (R) are true and (R) is the correct explanation of (A)
• B. (A) is false but (R) is true
• C. Both (A) and (R) are true but (R) is not the correct explanation of (A)
• D. (A) is true but (R) is false

Hint:

Choke coils are used to limit current in devices like fluorescent tubes, but the explanation involving voltage reduction is not correct in this context.

Answer 1

The Correct Option is D

The assertion is true because a choke coil is used to limit the current in a fluorescent tube by providing inductive reactance, thus preventing damage.
However, the reason is false because the voltage across the tube is not directly reduced by the factor involving \( R \) and \( L \) in the manner described. The choke coil primarily works by limiting the current rather than reducing the voltage in the manner stated in the reason.