A series – – circuit is connected to an alternating-voltage source of constant rms value
PHYSICS · Subjective · CBSE · Physics · Alternating Current · Alternating Current
Problem
A series R–L–C circuit is connected to an alternating-voltage source of constant rms value. The resistance is R=30Ω while the values of L and C are kept fixed.
(i) Explain qualitatively how the inductive reactance and the capacitive reactance vary with the frequency of the applied emf. State the mathematical relations involved.
(ii) On a single set of axes, sketch a qualitative graph of the impedance Z of the circuit versus the supply frequency f. Indicate clearly the point of resonance and the regions where the circuit behaves predominantly (a) inductively and (b) capacitively.
(iii) If the capacitance is doubled while R and L remain unchanged, show on the same axes how the Z–versus–f curve will be modified. State any two observable changes in the resonance characteristics of the circuit.