Question

Which of the following statements is true with reference to an L-C resonant circuit?

(1) The impedance of a parallel L-C circuit is low at resonance and higher at frequencies
above and below resonance. The impedance of a series circuit is high at resonance and
low at frequencies above and below resonance.
(2) The impedance of a parallel L-C circuit is high at resonance and lower at frequencies
above and below resonance. The impedance of a series circuit is low at resonance and
higher at frequencies above and below resonance.
(3) At resonance any L-C circuit exhibits lower impedance than at frequencies above
and below the resonant frequency.
(4) At resonance any L-C circuit exhibits higher impedance than at frequencies above
and below the resonant frequency.

Answer 1

Parallel:
impedance ----> infinity at resonance

Series
impedance ----> 0 at resonance (in reality to R because there is always some resistance)

Answer 2

1. FALSE: The impedance is max at resonance and min at frequencies above and below resonance. The impedance of a series resonant circuit is min at resonance and max at frequencies above and below resonance.

2. TRUE.

3. FALSE: The statement is true for the series resonant circuit only.

4. FALSE: The statement is true for the parallel resonant circuit only.