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What are hard and soft magnetic materials? Give examples.

Important Questions on Magnetism and Matter

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Physics>Electricity and Magnetism>Magnetism and Matter>Magnetic Properties of Materials

Magnetic materials used for making permanent magnets $(P)$ and magnets in a transformer $(T)$ have different properties of the following, which property best matches for the type of magnet required?

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Physics>Electricity and Magnetism>Magnetism and Matter>Magnetic Properties of Materials

Hysteresis loops for two magnetic materials

A

and

B

are given below:
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These materials are used to make magnets for electric generators, transformer core and electromagnet core. Then it is proper to use:

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Physics>Electricity and Magnetism>Magnetism and Matter>Magnetic Properties of Materials

Coercivity of a magnet where the ferromagnet gets completely demagnetized is

3 \times 10^{3} {Am}^{- 1}

. The minimum current required to be passed in a solenoid having

1000

turns per metre, so that the magnet gets completely demagnetized when placed inside the solenoid is

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Physics>Electricity and Magnetism>Magnetism and Matter>Magnetic Properties of Materials

Above the curie temperature the susceptibility of a ferromagnetic substance varies

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Physics>Electricity and Magnetism>Magnetism and Matter>Magnetic Properties of Materials

The coercivity of a small magnet, where the ferromagnet gets demagnetised is

3 \times 10^{3} A / m

. The current required to be passed in a solenoid of length

10 cm

and number of turns

100

, so that the magnet gets demagnetised when inside the solenoid is

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Physics>Electricity and Magnetism>Magnetism and Matter>Magnetic Properties of Materials

The meniscus of a liquid contained in one of the limbs of a narrow U -tube is placed between the poles of an electromagnet with the meniscus in a line with the field. The liquid is seen to rise to the line. This indicate that the liquid is ___ .

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Physics>Electricity and Magnetism>Magnetism and Matter>Magnetic Properties of Materials

The figure gives experimentally measured

B

vs.

H

variation in a ferromagnetic material. The retentivity, coercivity and saturation, respectively, of the material are:

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Physics>Electricity and Magnetism>Magnetism and Matter>Magnetic Properties of Materials

In a ferroelectric material, as the applied field is gradually reduced to zero, the polarization still left is known as

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Physics>Electricity and Magnetism>Magnetism and Matter>Magnetic Properties of Materials

Consider the regular array of vertical identical current-carrying wires (with the direction of current flow as indicated in the figure below) protruding through a horizontal table. If we scatter some diamagnetic particles on the table, they are likely to accumulate-

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Physics>Electricity and Magnetism>Magnetism and Matter>Magnetic Properties of Materials

An example of a perfect diamagnet is a superconductor. This implies that when a superconductor is put in a magnetic field of intensity

B

, the magnetic field

B_{s}

inside the superconductor will be such that

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Physics>Electricity and Magnetism>Magnetism and Matter>Magnetic Properties of Materials

The magnetic susceptibility of a paramagnetic substance at

- 173 ° C

1.5 \times 10^{- 2}

. To have the susceptibility

0.5 \times 10^{- 2}

, the change in temperature in

° C

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Physics>Electricity and Magnetism>Magnetism and Matter>Magnetic Properties of Materials

The magnetic susceptibility is negative for:

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Physics>Electricity and Magnetism>Magnetism and Matter>Magnetic Properties of Materials

Substances, when placed in a magnetic field acquire feeble magnetisation in the direction opposite to that of the applied field are called

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Physics>Electricity and Magnetism>Magnetism and Matter>Magnetic Properties of Materials

A perfectly diamagnetic sphere has a small spherical cavity at its centre, which is filled with a paramagnetic substance. The whole system is placed in a uniform magnetic field $\vec{B}$ . Then the field inside the paramagnetic substance is:

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