L1 - Hysteresis Loop And magnetic Properties Flashcards
Explain Retentivity
A measure of the material’s ability to retain a certain amount of residual magnetic field when the magnetizing force is REMOVED after achieving saturation.
Explain Residual Magnetism (aka Residual Flux)
- It is the magnetic FLUX DENSITY that remains in a material when the magnetizing force is ZERO
- Note that RESIDUAL MAGNETISM and RETENTIVITY are the same when the material has been MAGNETIZED to the SATURATION point.
Explain coercive force
The amount of REVERSE MAGNETIC FIELD which must be applied to a MAGNETIC MATERIAL to make the MAGNETIC FLUX to ZERO.
Define Permeability
A property of a material describing the ease which a MAGNETIC FLUX is established in the component.
Define reluctance
-Opposition that a ferromagnetic material shows to the establishment of a magnetic field.
- Reluctance is analogous to the resistance in an electrical circuit.
Briefly describe the variations in hysteresis curves.
WIDE HYSTERESIS LOOP:
-It RETAINS a large fraction of the saturation field when driving field is removed.
-Desirable for permanent magnet, magnetic recording and memory devices.
- Relative to other materials, a material with a wider hysteresis loop has:
LOWER permeability
HIGHER retentivity
HIGHER coercivity
HIGHER reluctance
HIGHER residual magnetism
NORMAL HYSTERESIS LOOP:
- ‘Saturation magnetization’. The area of the hysteresis loop is related to the amount of ENERGY DISSIPATION upon REVERSAL of the field.
NARROW HYSTERESIS LOOP:
- Implies a SMALL amount of DISSIPATED ENERGY in REPEATEDLY REVERSING the magnetization.
- Desirable for transformer and motor cores to MINIMIZE the energy dissipation fields associated with AC electrical applications.
Relative to other materials, a material with a narrower hysteresis loop has:
HIGHER permeability
LOWER retentivity
LOWER coercivity
LOWER reluctance
LOWER residual magnetism
