What is an inductor?

Question

Define

Answer 1

An inductor, also known as a coil, choke, or reactor, is a passive two-terminal electrical component that stores energy in a magnetic field when electric current flows through it1. Let’s break down the details:

1. Construction:
   • An inductor typically consists of an insulated wire wound into a coil shape.
   • When current flows through this coil, it generates a magnetic field around it.

2. Working Principle:
   • As the current changes within the coil, the time-varying magnetic field induces an electromotive force (emf) or voltage in the conductor. This phenomenon follows Faraday’s law of induction.
   • According to Lenz’s law, the induced voltage opposes the change in current that created it. In other words, inductors resist changes in current.

3. Inductance:
   • An inductor’s key property is its inductance, denoted by the symbol L.
   • Inductance represents the ratio of the voltage across the inductor to the rate of change of current.
   • The SI unit for inductance is the henry (H), named after the 19th-century American scientist Joseph Henry.
   • Typical inductance values range from 1 µH (microhenry) to 20 H (henry).

4. Magnetic Core:
   • Many inductors include a magnetic core made of materials like iron or ferrite inside the coil.
   • This core enhances the magnetic field and increases the inductance.

5. Applications:
   • AC Electronic Equipment: Inductors are widely used in alternating current (AC) circuits, especially in radio equipment.
   • Chokes: Inductors designed to block AC while allowing DC to pass are called chokes.
   • Filters: They are essential in electronic filters to separate signals of different frequencies.
   • Tuned Circuits: When combined with capacitors, inductors create tuned circuits used in radio and TV receivers.

The term “inductor” seems to have originated from Heinrich Daniel Ruhmkorff, who called the induction coil he invented in 1851 an inductorium1.

In summary, think of an inductor as a component that stores energy in its magnetic field, resisting changes in current flow.