A variable capacitor C is connected in series with a coil having inductance L. The cir cuit possesses stray capacitance CS which is  assumed to be constant and effectively in par allel with the variable capacitor C. When the capacitor is set to 2.0 nF the resonant fre quency of the circuit is 86.85 kHz, and when the capacitor is set to 1.0 nF the resonant fre quency is 120 kHz. Determine

A variable capacitor C is connected in series

with a coil having inductance L. The cir

cuit possesses stray capacitance CS which is 

assumed to be constant and effectively in par

allel with the variable capacitor C. When the

capacitor is set to 2.0 nF the resonant fre

quency of the circuit is 86.85 kHz, and when

the capacitor is set to 1.0 nF the resonant fre

quency is 120 kHz. Determine the values of

(a) the stray circuit capacitance CS and (b) the

coil inductance L.               

. A series R–L–C circuit comprises a 5µF

capacitor, a 4ohm resistor and a variable induc

tance L. The supply voltage is 10∠0◦ V at 

a frequency of 159.1 Hz. The inductance is

adjusted until the p.d. across the 4 ohm resistance

is a maximum. Determine for this condition (a)

the value of inductance, (b) the p.d. across each

component and (c) the Q-factor of the circuit.