# Electronics/Inductors

The foundation of modern electrical engineering was the discovery by Faraday that when the magnetic flux through a loop of wire was varied, a voltage was set up in the wire. This process is called electromagnetic induction.

- A conductor wound in the form of a coil is called an inductor (or solenoid)
- An inductor has a strong magnetic field that has many uses
- Inductance opposes current change

- An inductor may have its inductance increased by:-
- adding more turns
- introducing an iron core through the centre of the turns

## Inductance[edit | edit source]

Inductance is the property by which it opposes the change in current through a circuit.

L = Inductance in Henry N = Number of turns in wire coil A = Area of coil in square ² meter l = Average length of coil in meters

## Magnetic of Inductance[edit | edit source]

L = Inductor in Henrys

## Magnetic of Turns[edit | edit source]

- Φ = N B A

A-area of cross section of the coil

## Voltage of Coil's Inductance[edit | edit source]

- = -ξ

## Voltage of Coil's Turns[edit | edit source]

## Reactance[edit | edit source]

## Impedance[edit | edit source]

## Phase Angle[edit | edit source]

For an inductor without resistance, the voltage and current is out of phase by 90^{o} (π/2 radians).

For an inductor with resistance, the voltage and current is out of phase by θ:

- Tan θ = = 2πf L/R
_{L}

- Tan θ = = 2πf L/R

When there is a change of angle, the frequency also changes. This can be used to shift the frequency:

- f = ( 2π / Tanθ ) ( R
_{L}/ L )

- f = ( 2π / Tanθ ) ( R

As frequency is one over time:

- t = ( Tanθ / 2π ) (L / R
_{L})

- t = ( Tanθ / 2π ) (L / R

## Frequency Response[edit | edit source]

- , Shorted Circuit. I = 0
- , Opened Circuit. I ‡ 0
- , Shorted Circuit. I = V / 2 R
_{L}

I - can be drawn, at certain frequency the value of current does not change with. So this circuit can be used as a high pass filter.