There are three types of magnetic materials.Examples of magnetic materials are:
- Paramagnetic materials
- Diamagnetic materials
- Ferromagnetic materials
paramagnetic substances are those which are attracted by magnets and when placed in a magnetic filed move from weaker to stronger parts of the field.
Paramagnetic materials examples
Familiar examples are:
- crown glass
- solution of salts of iron and oxygen
Properties of paramagnetic materials
- If a bar of paramagnetic material is suspended in between the pole pieces of an electromagnet, it sets itself parallel to the lines of force.
- When a bar of paramagnetic material is placed in a magnetic filed the lines of force tend to accumulate in it.
- If a paramagnetic liquid is placed in a watch glass resting on the pole pieces of an electromagnet then it accumulates in the middle. It is because in the central region the field is the strongest. If the pole pieces are not close together the filed is strongest near the poles and the liquid moves away from the center giving an almost opposite effect.
- If one end of a narrow u-tube containing a paramagnetic liquid is placed with in the pole pieces of an electromagnet in such a manner that the level of the liquid is in the lie with the field, then on applying the field the level of the liquid rises. The rises in proportional to the susceptibility of the liquid.
- When a paramagnetic gas is allowed to ascend between the poles pieces of an electromagnet it spreads along the direction of the filed.
Diamgnetic substances are those which are repeled by magnets and when placed in magnetic field move from stronger to weaker part of the field.
Diamagnetic materials examples
Familiar examples of these are:
Properties of Diamagnetic materials
- When a diamagnetic substance is placed in a magnetic field it sets itself at right angles to the direction of the lines of force.
- When a diamagnetic material is placed with in a magnetic field the lines of force tend to go away from the material.
- When a diamagnetic substance is placed in a watch glass on the pole pieces of a magnet the liquid accumulates on the sides causing a depression at the center which is the strongest part of the field. When the distance between the pole pieces is larger, the effect is reversed.
- A diamagnetic liquid in a u-tube placed in a magnetic field shows as depression.
- When a diamagnetic gas is allowed to ascend between, the poles piece of an electromagnet it spreads across the field.
Ferromagnetic substances are those which are attracted by the magnets and can also be magnetized.
Ferromagnetic materials examples
Familiar examples are:
- cobalt and their alloys
Properties of Ferromagnetic Substances
- Ferromagnetic substance show the properties of the paramagnetic substance to a much greater degree.
- The susceptibility has a positive value and the permeability is also very large.
- The intensity of magnetisation I is proportional to the magnetising field H for small value.