The intensity of magnetisation I is plotted against the...

The intensity of magnetisation $I$ is plotted against the magnetising field $H$ for different substances. the curves $A$ and $B$ shown in the adjoining figure are associated with (a) soft iron and steel respectively (b) steel and soft iron respectively (c) a diamagnetic and paramagnetic substance respectively (d) a paramagnetic and diamagnetic substance respectively

The intensity of magnetisation $I$ is plotted against the magnetising field $H$ for different substances. the curves $A$ and $B$ shown in the adjoining figure are associated with
(a) soft iron and steel respectively
(b) steel and soft iron respectively
(c) a diamagnetic and paramagnetic substance respectively
(d) a paramagnetic and diamagnetic substance respectively

Key Concepts

Diamagnetism

Diamagnetism is a form of magnetism where materials exhibit a very weak and negative response to an applied magnetic field. Diamagnetic materials create an induced magnetic field in a direction opposite to the external field and do not display hysteresis or saturation effects.

Soft Magnetic Materials

Soft magnetic materials are characterized by high permeability and low coercivity, meaning they are easily magnetised and demagnetised. Their magnetisation curves typically reach saturation quickly and exhibit narrow hysteresis loops, making them ideal for applications that require rapid switching and minimal energy loss.

Paramagnetism

Paramagnetism occurs in materials that have unpaired electrons, which align with an external magnetic field to produce a weak, positive magnetisation. The magnetisation in paramagnetic materials increases linearly with the applied field and shows no hysteresis, distinguishing it from ferromagnetic behavior.

Magnetisation Curve

A magnetisation curve is a graph that plots the intensity of magnetisation (I) against the applied magnetising field (H). It is used to characterize how a material responds to magnetisation, revealing key features such as saturation, coercivity, and remanence.

Ferromagnetism

Ferromagnetism refers to the property of certain materials—such as soft iron and steel—to exhibit a strong, spontaneous magnetisation due to the alignment of magnetic domains. This results in non?linear magnetisation behavior, including saturation and hysteresis effects when the material is subjected to an external magnetising field.

Magnetic Hysteresis

Magnetic hysteresis describes the lag in the response of magnetisation to changes in the magnetising field in ferromagnetic materials. The hysteresis loop, which appears when plotting I versus H, provides insight into energy losses, coercivity, and the remanent magnetisation of the material.

Hard Magnetic Materials

Hard magnetic materials possess high coercivity and retain significant residual magnetisation even after the removal of the external field. Their wider hysteresis loops are indicative of the energy required to alter their magnetisation state, making them well-suited for permanent magnet applications.

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