Question

what is hysteresis loop.?
Give Note on electron theory of paramagnetism ?
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Answer 1

Answer:

$\Large\underline\mathfrak{Question}$

What is hysteresis loop.?

Give Note on electron theory of paramagnetism ?

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$\Large\bold\star\underline{\underline\textbf{Hysteresis Loop\:}}$

( see the provided diagram also ( given with the answer)

→ Hysteresis loop is the B-H curve for ferromagnetic materials. It gives the idea about the retentivity of ferromagnetic materials. Hysteresis loop for ferromagnetic material is shown in the given picture (with this answer). Curve abcdefa is known as hysteresis loop. It is obtained by magnetisation and demagnetisation of the magnetic material.

» B increases when H is increased. At point a , B becomes saturated. When H is decreased B does not follow the path oa, it follows path abcd. If we again increase the value of H; then B follows the path defa.

» In the curve bo and oe gives the measure of retentivity of the material.

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$\Large\bold\star\underline{\underline\textbf{Theory of Paramagnetism\:}}$

→ Paramagnetic material possesses some magnetic dipole moments due to the orbital and spin motion of electrons around their axis. Due to the thermal agitation the dipole moments are arranged randomly. Therefore the net dipole moment is zero. When external magnetic field is applied, the dipole moments align themselves in the direction of applied field. The dipole moments fail to attain significant alignment at ordinary temperature and field. Therefore, the paramagnetic material gets weakly magnetised.

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Hope it helped u.

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Answer 2

Answer:

hysteresis loop in British English

noun. a closed curve showing the variation of the magnetic flux density of a ferromagnetic material with the external magnetic field producing it, when this field is changed through a complete cycle.

When a ferromagnetic material is magnetized in one direction, it will not relax back to zero magnetization when the imposed magnetizing field is removed. ... The lack of retraceability of the magnetization curve is the property called hysteresis and it is related to the existence of magnetic domains in the material.