C The figure shows hysteresis curves for three different...

C The figure shows hysteresis curves for three different materials. A hysteresis curve is a plot of the magnetic field magnitude inside the material $(B)$ as a function of the externally applied field $\left(B_{0}\right)$. (a) Which material would make the best permanent magnet? Explain. (b) Which would make the best core for an electromagnet? Explain.

C The figure shows hysteresis curves for three different materials. A hysteresis curve is a plot of the magnetic field magnitude inside the material $(B)$ as a function of the externally applied field $\left(B_{0}\right)$.
(a) Which material would make the best permanent magnet? Explain.
(b) Which would make the best core for an electromagnet? Explain.

Key Concepts

Electromagnet Core

An electromagnet core is used to efficiently channel the magnetic field generated by an electric current. For such applications, materials with low coercivity and low hysteresis losses are preferred because they allow rapid magnetization and demagnetization, thereby improving the efficiency and responsiveness of the electromagnet.

Permanent Magnet

A permanent magnet is a material that maintains a strong, persistent magnetic field without the need for an external energy source. The ideal material for a permanent magnet exhibits high remanence and high coercivity, ensuring that it remains magnetized even when subjected to opposing magnetic fields.

Magnetic Hysteresis

Magnetic hysteresis refers to the lag between changes in the magnetization of a material and the external magnetic field applied to it, represented graphically by a hysteresis curve. This curve illustrates how a material’s magnetic flux density responds as the applied field cycles, demonstrating properties such as energy loss, remanence, and coercivity.

Remanence

Remanence is the residual magnetization that a material retains when the external magnetic field is removed. High remanence indicates that a material can maintain a significant magnetic field without continued external influence, which is a desirable property for permanent magnets.

Coercivity

Coercivity is a measure of the resistance of a magnetic material to becoming demagnetized, defined as the intensity of the reverse magnetic field required to bring the magnetization to zero. High coercivity materials are preferred for permanent magnets because they maintain their magnetization in the presence of opposing fields, while low coercivity is beneficial for applications where the magnetization must be easily reversed, such as in electromagnet cores.

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