Magnetic Flux

The total number of magnetic lines of force of a magnet is called magnetic flux. It is represented by phi (ϕ) and its unit is Weber.

MAGNETIC FLUX DENSITY

Magnetic flux per unit area is called magnetic flux density. It is given as B = ϕ/A.

Where "B" is the magnetic flux density, (ϕ) is the magnetic flux and "A" is the area. The unit of magnetic flux density is Weber/m2.it is also called tesla.

MAGNETIZING FORCE

When current is passed through a coil having length of m, meter and N, turn then the magnetizing force is given by the fallowing formula

H = NI / L A/m

Where "H" number of turns, "I" current "L" length of coil. Its unit is A/m.

ABSOLUTE AND RELATIVE PERMEABILITY OF A MEDIUM

The phenomena of magnetism and electro magnetism are dependent upon a certain property of the medium called its permeability. Every medium is supposed to posse's two permeability.

ABSOLUTE AND RELATIVE PERMEABILITY

For measuring relative permeability, vacuum or free space is chosen as the reference medium. It is allotted an absolute permeability of υ0 = 4π x 10-7 H/m. absolutely, relative permeability of vacuum with reference to its self-only. Hence, for free space,

Absolute permeability = υ0 = 4π x 10-7 H/m

Relative permeability = υ0 = 1

Now take other medium than vacuum. If its relative permeability, as compared to vacuum is υr, then its absolutes permeability is

υ = υ0 υr H/m

MAGNETIC FIELD DUE TO CURRENT IN STRAIGHT CONDUCTOR

When a current flows through a conductor, magnetic lines of force are set up which surround the conductor. If the conductor is a straight wire the magnetic lines of force are in the form of concentric circle around the wire. As shown in the fig Magnetic Field Direction to current in straight Conductor Circuit