An impedance coil whose resistance and inductance are 18 ohms and 3.82 mH, respectively, is connected in parallel with a series combination of a 5.3 uF capacitor and a variable resistor. For what value of resistance will the circuit be in resonance at 1000 cps?
Let series resistor and inductor combination be
Let series capacitor and resistor combination be
When these are connected in parallel the total impedance should be resistive, that is the condition for resonance.
i. e imaginary term of parallel combination of =0
Simplifying we have,
Substituting given inductor, capacitor resistor and frequency values we have,