ELECTRICAL MAGNETIC CIRCUIT

INTRODUCTION OF MAGNETISM:

Magnet have two opposite magnetic poles, which either attract or repel each other. These poles namely known as south or north pole. The magnetic force between these two poles are directly proportional to the magnetic strength of the poles and inversely proportional to the square of the distance.

F ∝ m₁ m_{2    &}   F ∝ 1 / d2

^or  F ∝ m1 m2 / d2    

Therefore, 

F ∝ m1 m2 / 4πµd2  

Where,

 m_{1 and} m_{2 denotes the magnetic strength of the two poles.}

_{µ - Permeability of any material.}

_{d- Distance between two poles}

• _{PROPERTY OF THE MAGNETIC MATERIAL:}

1. _{Any Magnet will attract iron and its alloys.}
2. The magnet has two poles, when it is kept freely, it comes to rest directing north and south directions.The end, which points toward the north called as north pole and the other, which directs toward the south, called as south pole.
3.  Like/Same poles repel and unlike poles attract each other.
4. If a magnet will be broken in pieces, each piece will act as separate magnet.
5. Magnet can imparts its property to any material.
6. Magnet will lose its property is following case:

• If heated, hammered or dropped from height.

2. MAGNETIC FIELD: 

 The area around the magnet or magnet pole is defined as magnetic field. 

Magnetic field curves are observable (above photo), these curve lines are called as magnetic lines of force. Magnetic force of line travels from north to south in AIR and from south to north in a material.

1. Magnetic Flux:

Definition: Total number of lines of force comprising of magnetic field is known as magnetic flux.simplest way to understand the magnetic flux is Total number of line radiated by magnetic material is defined as magnetic flux.

Magnetic flux is denoted by Φ (phi) and it's measured unit is Webers.

Therefore, the flux coming out of a N-pole of m weber is given by.

Φ = m. Wb

One this which is very important to keep in mind, Magnetic flux have no physical existence, nothing flows in magnetic field as in electric field currents flow in the circuit. Magnetic flux concept is truly imaginary.

Note: 

1. Magnetic flux flows from North to South in  AIR.

2. Whereas in material it's flow from South to North.

The above points are very important while marking thr direction of flux, current flow, mmf and induced emf.

2. COULOMB'S LAW OF MAGNETISM:

Definition: The magnetic force produce between two poles is directly proportional to THE PRODUCT of their pole strength and inversely proportional to the DISTANCE between them.

Fig.2 Magnetic Field

Where,

μ - Permeability of any material.

μ_{0 -} Permeability of free space or permeability constant (4π10⁷).

μ_{r -} Relative Permeability

d - Distance between two poles.

m¹ - Magnetic strength of one pole.

m² - Magnetic strength of another pole.

F ∝ m¹m²

F  ∝ 1 /d²

Therefore,

F = m¹m² / μ₀ μ_r d²

 

We will discuss about other basic terms of magnetic circuit in next session.