PHYSICS · Multi-part · A Level · Physics · Fields and their consequences · Fields and their consequences
Problem
Consider a series combination of a resistor R, an inductor L, and a capacitor C, connected to an AC source of rms emf V operating at angular frequency ω.
(i) Derive an explicit expression for the phase angle ϕ between the source voltage and the circuit current in terms of R, L, C, and ω.
(ii) Using your result, obtain the separate conditions under which the current (a) leads the source voltage, (b) lags behind it, and (c) is in phase with it.
(iii) For R=20Ω, L=50mH, C=100μF and a supply frequency of 50Hz, calculate the numerical value of ϕ (in degrees, correct to one decimal place) and state clearly whether the current leads or lags the voltage.