magnetism 2 Flashcards
What is retentivity?
Retentivity is the amount of magnetization present when the external magnetizing field is removed
What is coercivity?
Coercivity is the amount of reverse (negative H) external magnetizing field required to completely demagnetize the substance
How does the intensity of magnetization of diamagnetic and paramagnetic materials relate to the magnetizing force?
For diamagnetic and paramagnetic materials, the intensity of magnetization is directly proportional to the magnetizing force. Doubling the magnetizing force doubles the intensity of magnetization.
What is the effect of domains on each other in ferromagnetic materials?
In ferromagnetic materials, there is an effect of the domains on each other, which involves both reversible and non-reversible forces.
What do irreversible forces correspond to in ferromagnetic materials?
Irreversible forces correspond to the rotation of the domains as they attempt to align themselves with the external magnetic field in a series of ‘jerks’.
What do reversible forces correspond to in ferromagnetic materials?
Reversible forces correspond to the movement of domain boundaries, where some domains become larger at the expense of others when an external magnetic field is applied.
What is permeability?
The ratio of magnetic induction to magnetic intensity.
The measure of magnetization a material obtains in response to an applied magnetic field.
Denoted by the symbol μ.
What does magnetic permeability measure?
- A material’s resistance to the magnetic field.
- The degree to which a magnetic field can penetrate through a material.
Greater magnetic permeability means greater conductivity for magnetic lines of force.
What is magnetic susceptibility?
The measure of how much a material will be magnetized in an applied magnetic field.
What are the types of magnetic materials?
Diamagnetics
Paramagnetics
Ferromagnetics
What is diamagnetism?
- A very weak form of magnetism induced by a change in the orbital motion of electrons due to an applied magnetic field.
- Nonpermanent and persists only in the presence of an external field.
- Examples: Copper, Water, Bismuth, Zinc, Marble, Glass, Gold.
What is paramagnetism?
- The external magnetic field results in atomic magnetic effects, making each atom an elementary bar magnet.
- The sample becomes demagnetized quickly after the external field is removed.
- Higher temperatures make it more difficult to magnetize the sample.
Examples: Platinum, Iron oxide, Oxygen, Titanium, Aluminium.
What is ferromagnetism?
- Large magnetic flux density, useful for various practical applications.
- Strong magnetic induction due to the behavior of magnetic domains within the material.
Examples: Iron, Cobalt, Nickel.
