From Practical Electronics Handbook, Sixth Edition


An inductor is a component whose action depends on the magnetic field that exists around any conductor when a current flows through that conductor. When the strength of such a magnetic field (or magnetic flux) changes, a voltage is induced between the ends of the conductor. This voltage is termed an induced EMF, using the old term of EMF ( electromotive force) to mean a voltage that has not been produced by a current flowing through a resistor.

At one time inductors were invariably fairly large components and were used in domestic radios as well as in a variety of other applications, but modern inductors for signal use are often SMD components and though used to a much lesser extent in domestic radio are extensively employed in other devices. Inductors intended for 50 Hz AC mains are invariably large components, but the extensive use of switch-mode power supplies has reduced the need for these items, though they are still made in large quantities.

If we confine our attention to static devices such as coils and transformers rather than moving devices such as electric motors, the change of magnetic field or flux can only be due to a change in the current through one conductor. The induced EMF is then in such a direction that it opposes this change of current, and the faster the rate of change of current the greater is the opposing EMF. Because of its direction, the induced EMF is called a

Products & Services
EMF Meters
EMF meters detect and monitor harmful electric, magnetic or electromagnetic fields surrounding personal or work areas.
RF Inductors
RF inductors are special inductors designed to be used in radio frequency (RF) and microwave applications.
Current Sensors
Current sensors measure AC and/or DC current levels. They receive current inputs and provide outputs as analog voltage signals, analog current levels, switches, or audible signals.
Electrical Power Generators
Electrical power generators, also known as alternators, transform mechanical energy into electrical energy.  They can be used for backup or emergency power or as an alternator on board a vehicle. Generators can produce either AC or DC power and are typically powered by a fuel engine.
Magnetic Cores
Magnetic cores are doughnut-shaped magnetic materials that are used with inductors, transformers and electromagnets. They are also used as computer memory elements.

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