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An electrical device could be a passive two-terminal electrical part that stores energy in its force field. Inductors area unit designed to line up a strong field linking the unit, whereas capacitors area unit designed to line up a strong field of force between the plates. Inductance is measured in Henries (H). One Henry is that the inductance level that will establish a possible unit of 1 potential unit across the coil as a result of a modification within the current of 1 A/s through the coil.

Inductors have a range of response characteristics nearly like those of the electrical device. The inductance exhibits its true characteristics solely associate degree modification in voltage or current is created among the network.

Basic Inductors

  • They store energy in a very force field
  • An electrical device is basically a coil of wire with associate degree iron core.
  • The image for associate degree electrical device is:

What do inductors do?

  • Consider this circuit
  • What can happen once the switch is closed?
  • Lamp A will glow instantly
  • Lamp B will take some time to attain full brightness.


  • As the current starts to flow through the inductance, a magnetic flux starts to form around it…..
  • As this field forms, the magnetic flux lines pass the coils at intervals the inductance and induce a voltage across the inductor….
  • According to Lenz’s Law, this voltage will oppose the voltage that caused it…..
  • This opposing voltage restricts this build-up at intervals the circuit, therefore, it takes a short while for the bulb to achieve full brightness.

An inductor is made of a coil of conducting wire

Magnetic Fields

  • In the region shut a magnet there exists a magnetic flux, which could be delineated by magnetic flux lines identical as electrical flux lines.
  • Magnetic flux lines dissent from electrical flux lines during this they don’t have associate origin or termination purpose.
  • Magnetic flux lines radiate from the pole to the South Pole through the magnetic bar.
  • Continuous magnetic flux lines will arrange to occupy as small apart as potential.
  • The strength of flux during a} very given region is directly related to the density of flux lines in this region.
  • If not like poles of two permanent magnets unit brought on the magnets will attract, and conjointly the flux distribution is as shown below.

If like poles unit brought on, the magnets will repel, and thus the flux distribution is as shown.

If a nonmagnetic material, like glass or copper, is placed at intervals the flux ways shut a magnet, there’ll be associate degree nearly unnoticeable modification at intervals the flux distribution.

If a magnetic material, like soft iron, is placed at intervals the flux path, the flux lines will have the soft iron rather than the surrounding air as a results of the flux lines pass with larger ease through magnetic materials than through air. This principle place to use at intervals the shielding of sensitive electrical parts and instruments that will be stricken with stray magnetic fields.

The direction of the magnetic flux lines is found by swing the thumb of the right hand at intervals the direction of typical current flow and noting the direction of the fingers (commonly observed because of the correct hand rule)

The relation between the flux in inductance and thus the present through the inductance is given below.