Inductor I-V Equation in Action

What is the difference between inductance and inductive reactance?

Inductance is the property of a conductor to oppose the incoming current for a short duration. When current flows through an inductor, a magnetic field is formed whose direction can be determined by right hand thumb rule. This steadily rising magnetic field generates a voltage which oppose the incoming current. Hence this is also called as Back EMF. Inductive reactance is this opposing voltage measured in ohms since it restricts the flow of current through the inductor. It is directly proportional to frequency of applied signal.

What is mutual inductance?

When alternating current flows through an inductor it generates a time varying magnetic field around itself. When another inductor is placed near the first inductor, the magnetic field lines cuts it and generates a voltage across the second inductor. This property is called as mutual inductance and it is used in transformers to either step-up or step-down the voltage.

Why loops of wire are required to create an inductor?

When current flows through a straight wire, it creates magnetic field around the wire. When this current supply is stopped, the magnetic field decreases rapidly. However this decreasing magnetic field does not pass through any wire and does not create a back EMF required for an inductor to work. Hence by creating loops of wires the magnetic flux density increases and when current stops, the rapidly decreasing magnetic field cuts through the spiral wires generating back EMF.

The inductor is a passive element that is used in electronic circuits to store energy in the form of magnetic fields. It is usually a thin wire coiled up of several turns around a ferromagnetic material. Inductors are used in transformers, oscillators, filters, etc. The amount of energy that can be stored by the inductor in the form of the magnetic field is called inductance measured in Henry named after the famous scientist Joseph Henry.

Inductor works on the principle of one of Maxwell’s four equations which states that a changing electric field produces a changing magnetic field and vice versa. Unlike a capacitor, an inductor cannot sustain the stored energy as soon as the external power supply is disconnected because the magnetic field decreases steadily as it is responsible for current flow in that circuit in the absence of the power supply.