Magnetic Properties of Matter Physics - Magnetic Properties of Matter

The susceptibility of magnesium at 300K is 1.2 × 10^-5. At what temperature will the susceptibility increase to 1.8 × 10^-5?

The susceptibility of annealed iron at saturation is 5500. Find the permeability of annealed iron at saturation.

Assume that each iron atom has a permanent magnetic moment equal to 2 Bohr magnetons (1 bohr magneton equals 9.27 × 10^-24A-m²). The density of atoms in iron is 8.52 × 10²⁸ atoms/m³.

1. Find the maximum magnetization I in a long cylinder of iron.
2. Find the maximum magnetic field B on the axis inside the cylinder.

What are the advantages of using soft iron as a core, instead of steel, in the coils of galvanometers?

Can we have magnetic hysteresis in paramagnetic or diamagnetic substances?

Why is it not possible to make permanent magnets from paramagnetic materials?

The magnetic intensity Hat the centre of a long solenoid carrying a current of 2.0A, is found to be 1500A/m. Find the number of turns per centimetre of the solenoid.

A rod is inserted as the core in the current-carrying solenoid of the previous problem.

1. What is the magnetic intensity H at the centre?
2. If the magnetization I of the core is found to be 0.12Nm, find the susceptibility of the material of the rod.
3. Is the material paramagnetic, diamagnetic or ferromagnetic?

The coercive force for a certain permanent magnet is 4.0 × 10⁴A/m. Thia magnet is placed inside a long solenoid of 40 turns/cm and a current is passed in the solenoid to demagnetise it completely. Find the current.

When a ferromagnetic material goes through a hysteresis loop, its thermal energy is increased. Where does this energy come from?

To keep valuable instruments away from the earth's magnetic field, they are enclosed in iron boxes. Explain.

A paramagnetic material is kept in a magnetic field. The field is increased till the magnetization becomes constant. If the temperature is now decreased, the magnetization

1. Will increase.
2. Decrease.
3. Remain constant.
4. May increase or decrease.

The permanent magnetic moment of the atoms of a material is zero. The material:

1. Must be paramagnetic.
2. Must be diamagnetic.
3. Must be ferromagnetic.
4. May be paramagnetic.

When a ferromagnetic material goes through a hysteresis loop, the magnetic susceptibility:

1. Has a fixed value.
2. May be zero.
3. May be infinity.
4. May be negative.

The desirable properties for making permanent magnets are:

1. High retentivity and high coercive force.
2. High retentivity and low coercive force.
3. Low retentivity and high coercive force.
4. Low retentivity and low coercive force.

A perpendicular material is place in a magnetic fields. Consider the following statemetns:

1. If the magnetic field is increased, the magnetization is increased.
2. If the temperature is increased, the magnetization is increased.

1. Both A and B are true.
2. A is true but B is false.
3. B is true but A is false.
4. Both A and B are false.

The magnetic field inside a long solenoid having 50 turns/cm is increased from 2·5 × 10.3T to 2.5T when an iron core of cross-sectional area 4cm² is inserted into it. Find:

1. The current in the solenoid.
2. The magnetization I of the core.
3. The pole strength developed in the core.

When a dielectric is placed in an electric field, it gets polarized. The electric field in a polarized material is less than the applied field. When a paramagnetic substance is kept in a magnetic field, the field in the substance is more than the applied field. Explain the reason of this opposite behaviour.

A rod, when suspended in a magnetic field, stays in the east-west direction. Can we be sure that the field is in the east-west direction? Can it be in the north-south direction?

Do permeability and relative permeability have the same dimensions?