EEE/ETI 1202
CIRCUITS & NETWORK THEORY I
LECTURE 6
, Magnetic Circuits
• The space (or field) in which a magnetic pole
experiences a force is called a magnetic field.
Properties of magnetic lines of force.
• (i) Each magnetic line of force forms a closed loop i.e.
outside the magnet, the direction of a magnetic line of force is
from north pole to south pole and it continues through the
body of the magnet to form a closed loop.
• (ii) No two magnetic lines of force intersect each other.
• (iii) Where the magnetic lines of force are close together, the
magnetic field is strong and where they are well spaced out,
the field is weak.
• (iv) Magnetic lines of force contract longitudinally and widen
laterally.
• (v) Magnetic lines of force are always ready to pass through
magnetic materials like iron in preference to pass through
non-magnetic materials like air.
,Magnetic Flux (Φ)
• The total number of magnetic lines of force produced by a magnetic source
called magnetic flux. It is denoted by Greek letter Φ(phi)..
• Units are in Weber (Wb)
• The more the magnetic lines of force, the greater the magnetic flux and th
stronger the magnetic field.
• Magnetic Flux Density (B)
• The magnetic flux density is defined as the magnetic flux passing normally pe
unit area i.e.
, Absolute and Relative Permeability
• Permeability of a material means its conductivity for magnetic flux.
• The greater the permeability of a material, the greater is its conductivity fo
magnetic flux and vice-versa.
• The absolute (or actual) permeability *μ0 = of air or vacuum is 4π × 10−7 H/m.
• μr = 1 for air or non-ferrous materials
CIRCUITS & NETWORK THEORY I
LECTURE 6
, Magnetic Circuits
• The space (or field) in which a magnetic pole
experiences a force is called a magnetic field.
Properties of magnetic lines of force.
• (i) Each magnetic line of force forms a closed loop i.e.
outside the magnet, the direction of a magnetic line of force is
from north pole to south pole and it continues through the
body of the magnet to form a closed loop.
• (ii) No two magnetic lines of force intersect each other.
• (iii) Where the magnetic lines of force are close together, the
magnetic field is strong and where they are well spaced out,
the field is weak.
• (iv) Magnetic lines of force contract longitudinally and widen
laterally.
• (v) Magnetic lines of force are always ready to pass through
magnetic materials like iron in preference to pass through
non-magnetic materials like air.
,Magnetic Flux (Φ)
• The total number of magnetic lines of force produced by a magnetic source
called magnetic flux. It is denoted by Greek letter Φ(phi)..
• Units are in Weber (Wb)
• The more the magnetic lines of force, the greater the magnetic flux and th
stronger the magnetic field.
• Magnetic Flux Density (B)
• The magnetic flux density is defined as the magnetic flux passing normally pe
unit area i.e.
, Absolute and Relative Permeability
• Permeability of a material means its conductivity for magnetic flux.
• The greater the permeability of a material, the greater is its conductivity fo
magnetic flux and vice-versa.
• The absolute (or actual) permeability *μ0 = of air or vacuum is 4π × 10−7 H/m.
• μr = 1 for air or non-ferrous materials
