Theory- 12 :- Definition of inductance. Properties. Types of inductors and their application.

1. Definition of Inductance

An inductor is a passive two-terminal electronic component that stores energy in a magnetic field when electric current flows through it.

Inductance (L) is the property of an inductor to oppose any change in the electric current flowing through it. This opposition is created by the generation of a "back" electromotive force (EMF) that counters the change in current.

• SI Unit: The unit of inductance is the Henry (H), named after scientist Joseph Henry. One Henry is defined as the amount of inductance for which a current changing at one ampere per second produces an electromotive force of one volt.     

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2. Properties of Inductance

An inductor's behavior is defined by several key properties:

• Energy Storage: It stores energy within its magnetic field. The amount of energy stored is given by the formula:

• Where:

  • E = Energy in joules (J)

  • L = Inductance in Henries (H)

  • I = Current in amperes (A)

• Opposition to Change in Current: Its defining characteristic is its resistance to changes in current. This is due to the back EMF generated by the changing magnetic field, as described by Faraday's Law of Induction.

• Frequency-Dependent Impedance: An inductor's impedance (opposition to current flow) increases with the frequency of an alternating current (AC). This property, called inductive reactance ($X_L$), makes it useful for filters. It is calculated as:

  

  
  

Of course. Here are the theory notes on inductance, its properties, and inductor types, based on the information provided.

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3. Types of Inductors and Their Applications

Inductors are often classified by their core material, which dictates their properties and best applications.

Type of Inductor	Description	Common Applications
Air Core Inductor	Has no magnetic core. The winding is self-supporting or on a non-magnetic form (e.g., plastic). It has low inductance but no core losses.	High-frequency circuits like RF tuning circuits, filters, and snubber circuits.
Iron Core Inductor	Uses an iron core to achieve high magnetic permeability, allowing for higher inductance in a smaller size. Best for low frequencies.	Audio frequency equipment, power supplies, and low-frequency filters.
Ferrite Core Inductor	Uses a ferrite (ceramic) core with high magnetic permeability and high electrical resistance, reducing energy loss at high frequencies.	Switched-mode power supplies (SMPS), RF transformers, and noise filters.
Toroidal Core Inductor	The wire is wound on a donut-shaped (toroidal) core. This shape traps the magnetic field, minimizing electromagnetic interference (EMI).	High-frequency circuits, medical devices, and switching regulators.
Laminated Core Inductor	The core is made of thin, insulated iron sheets to reduce energy losses from eddy currents.	Power transformers and chokes in low-frequency power applications.
Multilayer Chip Inductor	Tiny, surface-mount devices (SMD) made by layering conductive coils. Ideal for compact, high-density circuits.	Mobile phones, computers, and other portable electronics.
Coupled Inductors	Two or more windings share a common magnetic core, allowing the magnetic field from one to induce a voltage in the other (e.g., transformers).	Power conversion (flyback converters) and signal isolation.