An inductor is a passive electrical component that stores energy in the form of a magnetic field when electric current flows through it. It typically consists of a coil of wire wound around a core, which can be air, iron, or ferrite.
Working Principle
When current passes through the coil, a magnetic field is created around it.
- If the current changes, the magnetic field also changes.
- This changing magnetic field induces an electromotive force (EMF) that opposes the change in current, according to Lenz’s Law. This property is called inductance (L), measured in Henries (H).
From the Inductor’s Point of View
- The inductor resists sudden changes in current.
- When the switch is turned ON, it initially opposes the flow of current but gradually allows it to increase.
- When the switch is OFF, it tries to maintain the current by releasing stored magnetic energy back into the circuit.
Key Effects You Can Observe
- The induced voltage across an inductor is proportional to the rate of change of current: V = L × (di/dt)
- Inductors allow DC (after initial resistance) but oppose AC, because alternating current constantly changes direction.
- In AC circuits, inductors cause the current to lag behind the voltage by 90°.
Real-World Example
In the animation:
- When Switch Sw1 is closed, Lamp A glows immediately (connected to the power source).
- The changing current through coil A creates a magnetic field that induces a current in coil B, lighting Lamp B.
- This shows the principle of mutual induction — the basis of transformer operation.
Applications
- Transformers (based on mutual induction)
- Filters in power supplies
- Energy storage in switching power supplies
- Chokes to block AC while passing DC
- Inductive sensors and motors
