Frequency and Inductors
At what frequency do inductors fail to pass an a.c. signal?
There is no frequency at which they start or stop. How well a particular
inductor works in an AC circuit depends on the rest of the circuit as much
as it depends on the inductor.
A particular inductor, with inductance L, responds to the rate at which the
current passing through it changes. The faster the current changes, the
more voltage is used by the inductor. In a circuit, an inductor limits the
rate at which the current can change. For an AC signal, the "inductive
reactance" of an inductor is 2(pi)fL: the product of
2*pi*frequency*inductance. This is the ratio of peak voltage across the
inductor to peak current through the inductor. Greater frequency means less
current. This is because greater frequency means the current changes more
quickly. Still, there is no real maximum frequency.
Dr. Ken Mellendorf
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Update: June 2012