A portable radio set contains a series RLC tuned circuit with a fixed inductance coil…
PHYSICS · Multi-part · A Level · Physics · Fields and their consequences · Fields and their consequences
Problem
A portable radio set contains a series RLC tuned circuit with a fixed inductance coil and a variable air-capacitor controlled by the tuning knob.
(a) State the electrical condition for resonance in such a circuit.
(b) Explain, with reasons, how turning the tuning knob enables the listener to select one particular broadcast frequency while rejecting other neighbouring frequencies.
(c) Describe how the phase difference between the circuit current and the supply voltage changes as the broadcast frequency is gradually increased from well below the resonant frequency to well above it.