A radio-tuning section consists of a fixed inductor of in series with a variable air…
PHYSICS · Multi-part · A Level · Physics · Fields and their consequences · Fields and their consequences
Problem
A radio-tuning section consists of a fixed inductor of L=0.20mH in series with a variable air capacitor whose capacitance can be adjusted continuously from 50pF to 250pF.
(a) Derive an expression for the frequency of electrical resonance of the series combination in terms of L and C.
(b) Using the expression obtained in (a), compute the lowest and highest resonance frequencies that can be achieved with the given range of capacitance.
(c) For the lowest resonance frequency found in (b), calculate the numerical values of the inductive reactance and the capacitive reactance, and confirm that they are equal in magnitude as required for resonance.