MAGNETIC CIRCUIT :- Magnetic flux in a closed loop or mesh is defined as the MAGNETIC CIRCUIT.
SOME TERMS USED IN MAGNETIC CIRCUITS ARE :
1.MAGNETIC FLUX :- Number of magnetic lines of force produced by a magnet is called Magnetic flux.It is denoted by ϕ.
2.MAGNETIC FIELD :- It is the region around the magnet where poles exhibit force of attraction or force of repulsion.
3.MAGNETIC FLUX DENSITY :- Magnetic lines of force per unit area at right angles to the flux. It is denoted by B. Its unit is TESLA.B = ϕ/A where ϕ denotes magnetic flux and A denotes area .
4.MAGNETIC INTENSITY OR MAGNETISING FORCE :- The force acting on a unit N-pole placed at a point in the magnetic field is called MAGNETIC FIELD INTENSITY at that point . It is denoted by H.
H = ℑ / l.
ℑ =applied MMF in ampere-turns
l =average length of the magnetic path in meter.
5. PERMEABILITY :- The ability of a magnetic material to allow magnetic lines of force to pass through it is known as MAGNETIC PERMEABILITY. It is denoted by (μ).
6. RELATIVE PERMEABILITY :- It is the ratio of permeability of material to the permeability of air . It is denoted by μr.
where μr = μ / μ0.
7. INTENSITY OF MAGNETISATION :- The pole strength developed per unit area of the bar is called INTENSITY OF MAGNETISATION. It is denoted by J.
8. MAGNETO MOTIVE FORCE :- It is the work done in moving a unit magnetic pole around the magnetic circuit is called MAGNETO MOTIVE FORCE (M.M.F).
M.M.F = NI Amphere turns.
where N = no of turns. and I = current .
9. RELUCTANCE :- It is the resistance offered to the magnetic flux by a magnetic circuit is called RELUCTANCE. It is denoted by S.
S = l / μ A .