A pure resistor of resistance ohm and a pure inductor of inductance henry are…
PHYSICS · Multi-part · A Level · Physics · Fields and their consequences · Fields and their consequences
Problem
A pure resistor of resistance R ohm and a pure inductor of inductance L henry are connected in series to an AC source of angular frequency ω. The circuit carries an rms current Irms.
Answer the following on the basis of phasor representation of the alternating quantities:
(i) With the current as the reference phasor, draw a neatly–labelled phasor diagram showing the rms voltages across the resistor and inductor as well as the supply rms voltage.
(ii) Explain, with reasons based on circuit behaviour, why the voltage across the resistor is in phase with the current whereas the voltage across the inductor leads the current by 90∘.
(iii) Using the diagram, show that the rms value of the supply voltage is equal to the vector (tip-to-tail) sum of the individual rms voltages across the resistor and the inductor.