In a parallel LC circuit, if the signal frequency is decreased below the resonant frequency, then ___________

The correct answer is: B. XL increases and XC decreases

In a parallel LC circuit, the inductive reactance (XL) is proportional to the frequency, while the capacitive reactance (XC) is inversely proportional to the frequency. Therefore, if the signal frequency is decreased below the resonant frequency, the inductive reactance will increase and the capacitive reactance will decrease. This will cause the line current to increase, as the impedance of the circuit will decrease.

Here is a more detailed explanation of each option:

• Option A: XL decreases and XC increases. This is not correct, as the inductive reactance (XL) is proportional to the frequency, while the capacitive reactance (XC) is inversely proportional to the frequency. Therefore, if the signal frequency is decreased below the resonant frequency, the inductive reactance will increase and the capacitive reactance will decrease.
• Option B: XL increases and XC decreases. This is the correct answer, as explained above.
• Option C: Line current becomes minimum. This is not correct, as the line current will increase, as the impedance of the circuit will decrease.
• Option D: None of the above. This is not correct, as option B is the correct answer.