There are many kinds of components that posses self-inductance. Such as, Solenoid coils, the loudspeakers and other few other devices that include a coil. Even the leads of a capacitor, resistor or transistor, though they do not have coil, possess few self-inductance at radio frequencies. In these cases the Inductance is very low and is thus ignorable, or may cause problems.
Inductance is a useful attribute of certain other type of components. These include the following:
The chokes are effectively applied for blocking high-frequency signals so that they cannot pass through from one part of a circuit to another. Low-frequency signals or DC voltage levels has the ability to pass through. Large chokes look like transformers, but contain only one coil. Small chokes has beads or collars that are composed of ferrite, and are threaded on to the wire that is carrying the high frequency signals.
Ferrite is an iron-containing material, and this makes it to act as a core to contain the lines of magnetic force around the wire. Sometimes a choke is made by simply winding the wire around a ferrite ring.
Tuning coils are used in radio transmittters and receivers for tuning the circuit to a particular radio frequency. The coil is wound on a plastic former. It may contain a core of ferrite or iron dust ceramic that can be screwed in or out of the coil for tuning it. When it has a connection with a capacitor, it forms a tuned network that resonates at a particular frequency, as discussed in the coming paragrapghs.
The inductor may be a few turns of wire wound on a plastic former, as shown in diagram 7.4 above. There may be more than one winding on a tuned circuit, and is equivalent to a transformer that operates best at one particular frequency. More than one coil is wound on a plastic former. The iron-dust core is threaded just like inside of the former. The core is moved into or out of the coil by way of turning it with a special non-magenetic tool so that it does not introduce spurious magnetic effects. This enables the self inductance of the coil to adjust itself in precise way. Such types of inductors are used in the same way as the capacitors are used, in order to couple two parts of a circuit. However, they are best useful only for radio-frequency signals.