# CRTC Electronics

### Inductors

Lesson Plan part 1 An inductor or a reactor is a passive electrical component that can store energy in a magnetic field created by the electric current passing through it. An inductor's ability to store magnetic energy is measured by its inductance (L), in units of henries (H). Typically an inductor is a conducting wire shaped as a coil, the loops helping to create a strong magnetic field inside the coil due to Ampere's Law. Due to the time-varying magnetic field inside the coil, a voltage is induced, according to Faraday's law of electromagnetic induction, which by Lenz's Law opposes the change in current that created it. Inductors are one of the basic electronic components used in electronics where current and voltage change with time, due to the ability of inductors to delay and reshape alternating currents. In everyday speak inductors are sometimes called chokes, but this refers to only a particular type and purpose of inductor.

Inductor

Reactor

Choke

Coil

Electric Magnet

# Henries

The capacity of an inductor is controlled by four factors:

• The number of coils - More coils means more inductance.
• The material that the coils are wrapped around (the core)
• The cross-sectional area of the coil - More area means more inductance.
• The length of the coil - A short coil means narrower (or overlapping) coils, which means more inductance.

Putting iron in the core of an inductor gives it much more inductance than air or any non-magnetic core would.

The standard unit of inductance is the henry. The equation for calculating the number of henries in an inductor is:

H = (4 * Pi * #Turns * #Turns * coil Area * mu) / (coil Length * 10,000,000)