rather than re-writing this in my own words: Chokes definitelty have something to do with AC.
A
ferrite bead is a passive electric component used to suppress high frequency
noise in electronic circuits. It is a specific type of
electronic choke. Ferrite beads employ the dissipation of high frequency currents in a
ferrite ceramic to build high frequency noise suppression devices. Ferrite beads may also be called blocks,
cores, rings, EMI filters, or chokes.
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The name comes from blocking—“choking”—high frequencies while passing low frequencies. It is a functional name; the same inductor is often called a “choke” if used to block higher frequencies, but a “coil” or “inductor” if, say, part of a
tuned circuit.
Ferrite beads are one of the simplest and least expensive types of interference filters to install on preexisting electronic cabling. For a simple ferrite ring, the wire is simply wrapped around the core through the center typically 5 or 7 times. Clamp-on cores are also available, which can be attached without wrapping the wire at all. Although the wire is not coiled around the core for this type of ferrite bead, the introduction of the ferrite core around the wire increases the self-inductance of the wire and thus still has the effect of absorbing energy from the noise traveling in the wire. If the fit is not snug enough, the core can be secured with
cable ties, or if the center is large enough, have the cabling looped through one or more times. Small ferrite beads may be slipped over component leads to suppress
parasitic oscillation.
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[size=x-small]A choke is a coil of insulated wire, often wound on a magnetic core, used as a passive inductor which blocks higher-frequency alternating current (ac) in an electrical circuit while passing signals of much lower frequency and direct current by having an impedance largely determined by reactance, which is proportional to frequency. Chokes are typically used as the inductive components in electronic filters.[/size]
[size=x-small]Alex[/size]