What is an inductor, and what is its function?

Short Answer:

An inductor is a passive electrical component that stores energy in the form of a magnetic field when current flows through it. It is usually made of a coil of wire wound around a core, and it resists sudden changes in current.

The main function of an inductor is to oppose changes in current, filter signals, and store energy in electrical and electronic circuits. Inductors are commonly used in transformers, motors, filters, and power supply systems where magnetic field-based energy handling is needed.

Detailed Explanation:

Inductor

An inductor is a two-terminal component that stores electrical energy in a magnetic field created around its coil when current flows through it. It is made by winding a conducting wire into a coil, often around a magnetic or air core. The magnetic field builds up as current flows and collapses when the current decreases or stops.

The property of an inductor is called inductance, and it is measured in henries (H). The greater the number of turns or the more magnetic the core, the higher the inductance. The formula that relates voltage and inductance is:
V = L × (di/dt)
Where:

  • V = voltage across the inductor
  • L = inductance in henries
  • di/dt = rate of change of current

This means that the voltage induced across an inductor is directly proportional to how fast the current is changing.

Function of an Inductor

  1. Opposing Sudden Changes in Current
    • An inductor resists quick changes in current flowing through it.
    • When current tries to increase suddenly, the inductor generates a voltage that opposes the change.
    • This makes it useful in smoothing currents in circuits.
  2. Energy Storage
    • Inductors store energy temporarily in the form of a magnetic field.
    • When the current stops, the magnetic field collapses and releases the stored energy back to the circuit.
    • This is used in switching power supplies and energy backup systems.
  3. Filtering and Signal Tuning
    • In combination with capacitors, inductors are used in filters to block certain frequencies and allow others.
    • In radios and communication circuits, they help in tuning and selecting specific frequencies.
  4. Choke Coils
    • Inductors are used as chokes to block high-frequency noise while allowing low-frequency or DC currents to pass.
    • They are widely used in power supply circuits to clean the output signal.
  5. Transformers and Magnetic Devices
    • Inductors are a key part of transformers where two coils (primary and secondary) transfer energy via magnetic fields.
    • They are also used in motors and inductive sensors.
  6. Inductive Reactance
    • Inductors introduce inductive reactance, which increases with frequency.
    • This property is used to control current in AC circuits and in designing frequency-dependent components.

Types of Inductors

  • Air Core Inductors: No magnetic core; used in high-frequency circuits
  • Iron Core Inductors: Higher inductance, used in low-frequency applications
  • Ferrite Core Inductors: Compact, used in switching regulators and filters
  • Variable Inductors: Inductance can be adjusted by changing core position

Each type is selected based on frequency, current handling, and application need.

Conclusion:

An inductor is an essential component that stores energy in a magnetic field and resists changes in current. Its main functions include current control, signal filtering, energy storage, and noise suppression. Inductors play a vital role in power electronics, communication systems, and electromagnetic devices, ensuring smooth and efficient operation.