Answer & Solution
Answer: Option D
Solution:
In a parallel resonant circuit, the resonance occurs when the inductive reactance (XL) and capacitive reactance (XC) are equal in magnitude but cancel each other out, resulting in a minimum impedance.
The bandwidth of a resonant circuit is determined by the difference between the frequencies at which the impedance is half the minimum value (half-power points). In other words, it's the range of frequencies over which the circuit remains close to its resonant condition.
When resistance in parallel with the circuit is reduced, it means that the total impedance of the circuit becomes primarily determined by the resistive component. This has the effect of reducing the difference between the frequencies at which the impedance is half the minimum value.
As a result, the bandwidth of the parallel resonant circuit decreases, and the resonance becomes sharper because it becomes more selective to a narrower range of frequencies.
Option D: Decreases is the correct answer.
