What is relative permeability of copper and aluminium poor?
Answers
Answer:
Explanation:
In electromagnetism, permeability is the measure of the resistance of a material against the formation of a magnetic field, otherwise known as distributed inductance in transmission line theory. Hence, it is the degree of magnetization that a material obtains in response to an applied magnetic field. Magnetic permeability is typically represented by the (italicized) Greek letter μ. The term was coined in September 1885 by Oliver Heaviside. The reciprocal of magnetic permeability is magnetic reluctivity.
In SI units, permeability is measured in henries per meter (H/m), or equivalently in newtons per ampere squared (N⋅A−2). The permeability constant μ0, also known as the magnetic constant or the permeability of free space, is a measure of the amount of resistance encountered when forming a magnetic field in a classical vacuum. Until 20 May 2019, the magnetic constant had the exact (defined)[1] value μ0 = 4π × 10−7 H/m ≈ 12.57×10−7 H/m.
On 20 May 2019, a revision to the SI system went into effect, making the vacuum permeability no longer a constant but rather a value that needs to be determined experimentally;[2] 4π × 1.00000000082(20)×10−7 H⋅m−1 is a recently measured value in the new system. It is proportional to the dimensionless fine-structure constant with no other dependencies.[3][4]
A closely related property of materials is magnetic susceptibility, which is a dimensionless proportionality factor that indicates the degree of magnetization of a material in response to an applied magnetic field.
Explanation:
Characteristics of diamagnetic materials
3. It does not depend on temperature and the strength of applied magnetic field.
4. No magnetic moment is present in the material.
Paramagnetic Materials
Definition
Paramagnetic materials become weakly ionized when placed in a magnetic field in the same direction as that of the applied field. It has permanent dipole moment in each atom. When external magnetic field is applied, the induced magnetic moment is produced which increase the magnetic induction present in the specimen.
Origin
The orientation of the magnetic moment along the direction of the external field gives rise to paramagnetism. The permanent magnetic moment arises due to orbital motion of electron around the nucleus and spin motion of electron about its own axis. The magnetic moment due to former disappears due to the effect of electric field of the neighbouring charges. But the magnetic moment due to electron spin are randomly oriented in the absence of external field. When the external field is applied, the magnetic moments tend to align in the direction of the applied field resulting in large magnetization. But due to the thermal agitation of the atoms the magnetic moments are partially aligned in the direction of the external field resulting in weak magnetization.
Characteristics
1. Susceptibility ( m) is positive and small.
Example For aluminum, ( m) = 0.065 x10-6
For Calcium, ( m) = 1.10 x10-6
The relative permeability μr > 1.
2. When magnetic field is applied to paramagnetic material, it is attracted towards the centre of the material.
3. Susceptibility is inversely proportional to absolute temperature of the material. m α (1/T)
Curie’s law for high temperature m = (C/T)
T = absolute temperature in Kelvin; C = Curie constant
1. Diamagnetic materials
E.g: Cadmium, Copper, Silver, Bismuth, Tin, zinc, Gold, Niobium and its compounds.
2. Paramagnetic materials
E.g: Aluminum, Calcium, Oxygen, Platinum, Titanium and Chromium.
3. Ferromagnetic materials
E.g:
a. Ferromagnetic materials
E.g: Iron, Cobalt, Nickel
b. Anti-ferro magnetic materials
E.g: Ferrous oxide, Manganese oxide, Zinc ferrite
c. Ferrimagnetic materials
E.g: Nickel ferrite, Manganese ferrite, Ferrous ferrite
Diamagnetic Materials
Definition
These materials when placed in a magnetic field, becomes weakly magnetized in the direction opposite to that of the applied field. There is no permanent dipole moment in each atom. The induced magnetic moment produced in these materials during the application of the external magnetic field decreases the magnetic induction present in the specimen.
Origin
A material contains a large number of electrons and the orbits of these electrons are randomly oriented in space. The current that is produced due to movement of electron in an orbit produces magnetic field in a direction at right angles to the plane of the orbit. This magnetic field induces a magnetic moment in the atom in a direction opposite to it. These magnetic moments are randomly oriented. Hence the magnetic moments of all such electron gets cancelled resulting in the net magnetism equal to zero in the material.
When an external magnetic field is applied to the material, rotation of dipoles take place producing an induced dipole moment: This induced dipole moment opposes the applied field. The magnetism which is created in a direction opposite to that of the external field is called diamagnetism.
Characteristics of diamagnetic materials
1. Susceptibility ( m) of a diamagnetic material is always negative. The relative permeability μr < 1.
Example For Cadmium, ( m) = - 0.18 x10-6
For Copper, ( m) = - 0.086 x10-6
For Silver, ( m) = - 0.2 x10-6
2. When magnetic field is applied, it repels the magnetic lines of force. This property is exhibited by superconductors. Hence we call all superconducting materials (at low temperature) as perfect diamagnet. When the temperature is increased beyond it critical temperature, diamagnetism suddenly disappears and it behaves like a normal conducting material.
3. It does not depend on temperature and the strength of applied magnetic field.
4. No magnetic moment is present in the material.
Paramagnetic Materials
Definition
Paramagnetic materials become weakly ionized when placed in a magnetic field in the same direction as that of the applied field. It has permanent dipole moment in each atom. When external magnetic field is applied, the induced magnetic moment is produced which increase the magnetic induction present in the specimen.
Origin
1. Susceptibility ( m) is positive and small.
Example For aluminum, ( m) = 0.065 x10-6
For Calcium, ( m) = 1.10 x10-6