Question
What is the magnitude of the current at the input of a parallel RLC circuit at resonance?
Answer Options
- A) Minimum
- B) Maximum
- C) R/L
- D) L/R
Correct Answer: A
Explanation
A parallel RLC circuit acts as a tank circuit used for frequency selection. At the resonant frequency, the external current flowing into the circuit (from the power source) is the sum of the current through the resistor (R) and the net current through the inductor-capacitor (LC) combination. Since the inductive current and capacitive current are equal and opposite at resonance, they cancel each other out.
Because the net reactive current is zero, the total current drawn from the source is minimized and is equal only to the current flowing through the parallel resistive element. Therefore, the magnitude of the current at the input of a parallel RLC circuit at resonance is at its Minimum value. This characteristic is often used to filter out unwanted frequencies or to provide a high impedance load to a driving source.
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