Applications of super conductors:
1. Data storage (Memory Cell) in Computers
2. Superconducting magnets have been used to
levitate trains above its rails.
3. Superconducting materials are used to produce
very high magnetic fields of the order of 20T to
50T so super conductors are used as super
conductor magnets.
4. Electric generators and generators.
5. Since there is no loss of power (zero resistivity)
super conductors are used transmission of power
over very long distances.
6. They are used to determine the unknown
structure of chemical compounds, molecular
structure of unknown compounds.
7. Superconducting coils are also used in electric
machines, transformers and magnetic resonance
imaging (MRI) instruments. MRI is used to scan
human body.
Magnetic field intensity (H):
The magnetic field intensity (H) at any point in the magnetic field is
the force experienced by a north pole placed in the magnetic field.
Units: Ampere/meter
Magnetic Induction or Magnetic flux (B):
is defined as in any material the number of magnetic lines of force
passing through unit area perpendicularly.
Units: Weber/ meter2 ( Web/ m2) or Tesla.
`
Magnetization and Intensity of Magnetization (M):
The term magnetization is the process of the converting a non
magnet material into magnetic material. It is measure of
magnetization of a specimen.
Permeability (µ):
It indicates, with which the material allows magnetic lines of force to
pass through it.
Magnetic permeability is defined as the “ ratio between the
magnetic flux density (B) and magnetic field intensity (H)”.
𝐌𝐚𝐠𝐧𝐞𝐭𝐢𝐜 𝐟𝐥𝐮𝐱 𝐝𝐞𝐧𝐬𝐢𝐭𝐲 (𝐁)
Permeability (µ) =
𝑴𝒂𝒈𝒏𝒆𝒕𝒊𝒄 𝒇𝒊𝒆𝒍𝒅 𝒊𝒏𝒕𝒆𝒏𝒔𝒊𝒕𝒚(𝑯)
or B= µH
‘µ’ also called as the absolute permeability of the medium.
Units: Henry/meter (H/m)
If the medium is air or vacuum then
B=µ0 H
µ0=permeability of free space i.e. air or vacuum
µ0 =4𝜋 ×10-7 H/m
Relative Permeability (µr):
The ratio between the absolute permeability of the medium (µ) to
permeability free space (µ0)is called as “Relative Permeability (µr)”.
Relative Permeability (µr)
Absolute permeability of the medium (µ)
=
Permeability free space (µ𝟎 )
µr = µ/ µ0
µ = µ0 µr
Magnetic Susceptibility (𝜒):
Magnetic susceptibility is the measures of how much a
material will be magnetized in an applied magnetic field .
OR
Magnetic Susceptibility (𝜒) of material is defined as the ratio between
the intensity of magnetization (M) to applied magnetic field.
𝑰𝒏𝒕𝒆𝒏𝒔𝒊𝒕𝒚 𝒐𝒇 𝒕𝒉𝒆 𝑴𝒂𝒈𝒏𝒊𝒕𝒊𝒛𝒂𝒕𝒊𝒐𝒏(𝑴)
Magnetic Susceptibility (𝝌) =
𝑨𝒑𝒑𝒍𝒊𝒆𝒅 𝑴𝒂𝒈𝒏𝒆𝒕𝒊𝒄 𝑭𝒊𝒆𝒍𝒅(𝑯)
𝑴
Magnetic Susceptibility (𝝌) =
𝑯
It has no units.
Soft Magnetic Materials and Hard Magnetic Materials:
Depends on magnetization magnetic materials are
classifieds in to two groups .They are
1. Soft Magnetic Materials and
2. Hard Magnetic Materials
A type of magnetic material which can be easily magnetized
and demagnetized is known as soft magnetic material.
A type of magnetic material which cannot be easily
magnetized and demagnetized is known as hard magnetic
material.
OR
Differences between soft and hard magnetic materials
based on area of the hysteresis loop, they are classified as
soft and hard magnetic materials.
Difference between Hard Magnetic Material and Soft
Magnetic Material:
The major differences between the hard magnetic materials
and the soft magnetic materials are listed in the following
table −
Soft magnetic materials Hard magnetic materials
1. They have small 1. They have large hysteresis
hysteresis loss due to loss due to large area of
small area of hysteresis hysteresis loop.
loop
2. The domain wall
movement is difficult due to
2. The domain wall
presence of impurities
movement is easier. crystal imperfections.
3. The coercively(-Hc) and
3. The coercively (-Hc)and retentively (Mr) are large.
retentively (Mr) are
4. They cannot be easily
small.
magnetized and
demagnetized.
4. They can be easily
magnetized and
demagnetized.
5. The values of permeability
and susceptibility are small
5. The value of
permeability and
susceptibility are large.
6. Magnetization energy is 6. Magnetization energy is
small. large
7. Example:
7. Examples: ferrites, Fe-Si
Al-Ni-Co, Cu-Ni-Fe, Cu-Ni-Co
alloy, Fe-Ni alloy etc
8. They are used in loud
8. They are used in speakers, electrical
electrical motors, measuring instruments, for
production of permanent
generators,
magnets which are used in,
transformers, telephone
microphones etc.
receivers, RADARS.
storage of data,
switching circuits etc.
