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Reactance and current

QUESTION: When the frequency of AC circuit is decreased it is found that the current in the circuit increases. Which element is MOST likely in the circuit?
(a) resistor
(b) inductor
(c) capacitor
(d) capacitor and resistor
(e) inductor and capacitor


In order for the current to increase we need the reactance (X) of the circuit to decrease since for an ac circuit I = V/X.
For the inductor the reactance (XL) is proportional to f and so a decrease in frequency will cause and increase in the reactance (X) and so an increase in the current.

(b) is the correct answer.
© Keith Gibbs 2011