According to Faraday’s law of electromagnetic induction, “Whenever there is a change in current flowing through a coil, a change in magnetic field is produced which induces a voltage across the coil.” A coil is nothing but a twisted wire. When such a coil is formed out of a wire of certain length and cross-sectional area, it acts as an inductor.
The electromagnetic field produced by the inductor depends on the current flowing through it. The field so formed expands with an increase in current and contracts with decrease in current.
What is an Inductor?
Unit of Inductance
Symbol of inductance
Current voltage relationship in inductance
V is the voltage across the inductor in volts and i is the current flowing through it.
Power absorbed by an inductor
Energy stored in an inductor
Key points about inductor that has to be noted
- Refer equation 1, the voltage across an inductor depends on the change in current through it. Hence when the current is constant, the voltage across its terminals would fall to zero. This means that for a DC supply (constant current supply), inductor acts as short circuit.
- An inductor can store finite amount of energy even if the voltage across its terminal is zero.
- As mentioned before, an inductor should never dissipate energy. But practically, a small amount of energy dissipation occurs across an inductor due to the resistance of the coil.