Two identical coils of inductance and capacitance are connected separately in series…
PHYSICS · Subjective · A Level · Physics · Fields and their consequences · Fields and their consequences
Problem
Two identical coils of inductance L and capacitance C are connected separately in series with two different resistances R1 and R2(R2>R1) to the same a.c. source of variable frequency.
(a) On the same axes, sketch two resonance curves (current amplitude Im versus frequency f) corresponding to the two circuits and label them clearly.
(b) Identify which curve corresponds to R1 and which to R2.
(c) Explain qualitatively why the height and width of the resonance curve change when the resistance is increased from R1 to R2.
(d) State how this change affects the selectivity of the circuit in practical applications such as radio tuning.