What Determines the Frequency of an Inductor?
Because of electromagnetic effects, inductors increasingly resist an alternating current at high frequencies. Engineers use this frequency-dependent phenomenon to remove unwanted frequencies from a signal in some applications, and emphasizing desired frequencies in others.
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Description
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An inductor is a wire coil. When an electric current flows through an inductor, a magnetic field forms around it. How much magnetism forms depends on the number of turns or loops in the coil, and other details.
The Henry
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Inductance is measured in units called henries. An inductor of one henry will produce a voltage difference of one volt across its leads when current is changing at the rate of one ampere per second through it.
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Lenz's Law
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The magnetism produced by the inductor momentarily resists the flow of current. This is called Lenz's Law and results from electrical energy changing to magnetic energy and back again.
Frequency
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Signals flow through an inductor in inverse relation to their frequency. Low frequencies and DC flow easily; high frequencies become increasingly blocked, according to Lenz's Law.
Reactance
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The property of blocking signals by an inductor is called reactance. Reactance is similar to resistance, except it's frequency-related. The following formula determines an inductor's reactance:
X = 2 x pi x f x L
Where X is the reactance in ohms, f is frequency in cycles per second, and L is inductance in henries.
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References
- Photo Credit drosselspulen in der hand, induction coil image by Sascha Zlatkov from Fotolia.com
