Name: Ferromagnetism
Uploaded: 2019-07-19
Duration: 4 min 22 s
Description: We use the strongest magnetic substances as electromagnets almost everywhere in our modern lives. Do you know what they are? We will discuss ferromagnetism i...

Question

What is hysteresis? Define the terms 'coercivity' and 'retentivity' of a ferromagnetic material.

Accepted Answer

Hysteresis: The phenomenon of lagging behind the magnetic induction ( $\vec{B}$ ) with respect to the magnetizing field ( $\vec{h}$ ) is called hysteresis. This happens when an external magnetic field is applied to a ferromagnet such as iron and the atomic dipoles are aligned with it.

Coercivity: The magnetizing field ( $H$ ) needed to demagnetize the magnetic material completely is known as coercivity. In simple words, coercivity is the minimum value of magnetising intensity that is required to bring the material to its original state. In the case of a ferromagnetic substance, when the applied magnetic field is increased in the reverse direction, then at some point the substance completely loses its magnetization. This point is known as coercivity.

Retentivity: The property of the magnetic material to retain magnetism even in the absence of the magnetizing field is known as retentivity or remanence. Or in other words when the applied magnetic field is decreased to zero after meeting the saturation point of magnetization, then the remaining magnetization shown by the substance is known as retentivity.

What is hysteresis? Define the terms 'coercivity' and 'retentivity' of a ferromagnetic material.

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