Electronics/Inductors

From Wikiversity
Jump to: navigation, search

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]

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

Magnetic of Inductance[edit]

Magnetic of Turns[edit]

Φ = N B

Voltage of Coil's Inductance[edit]

= -ξ

Voltage of Coil's Turns[edit]

Reactance[edit]

Impedance[edit]

Phase Angle[edit]

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

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

Tan θ = = 2πf L/RL

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

f = ( 2π / Tanθ ) ( RL / L )

As frequency is one over time:

t = ( Tanθ / 2π ) (L / RL )

Frequency Response[edit]

, Shorted Circuit. I = 0
, Opened Circuit. I ‡ 0
, Shorted Circuit. I = V / 2 RL

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.