# What is a composite magnetic circuit

## Magnetic circuit

The closed path followed by lines of magnetic force is called Magnetic circuit. By doing Magnetic circuitThe magnetic flux or line of magnetic force starts at one point and ends at the same point after it finishes its path. The flux is generated by magnets; it can be a permanent magnet or an electromagnet.

A Magnetic circuit consists of magnetic materials with high permeability such as iron, mild steel, etc. Magnetic circuits are used in various devices such as the electric motor, transformers, relays, generator galvanometers, etc. Suppose a solenoid had N turns on an iron core. The magnetic flux of ø Weber is established in the core when the current of I amps is passed through a solenoid.

Let l = mean length of the magnetic circuit
A = cross-sectional area of ​​the core
µr = relative permeability of the core
Now the flux density in the core material

Magnetizing force in the core

According to labor law, the work done in moving a unit pole after the magnetic circuit is equal to the ampere-turns enclosed by the magnetic circuit.

The above equation explains the following points

1. Directly proportional to a number of turns (N) and current (I). It can be seen that the flux increases when the number of turns or the current increases and decreases when either of the two quantities decreases. NI is the magnetomotive force (MMF).
2. Inversely proportional to l/a µ0µr, where from (l/a µ0µr) is called reluctance. The lower the reluctance, the higher the flux and vice versa.