Property

Diamagnetic substances

Paramagnetic substances

Ferromagnetic substances

Cause of magnetism

Orbital movement of electrons

Spin motion of electrons

Formation of domains

Explanation of magnetism

On the basis of orbital motion of electrons

On the basis of spin and orbital motion of electrons

On the basis of domains formed

Behavior In a non-uniform magnetic field

These are repelled in an external magnetic field i.e. have a tendency to go from high to low field region.

These are feebly attracted in an external magnetic field i.e., have a tendency to go from low to high field region

These are strongly attracted in an external magnetic field i.e. they easily go from low to high field region

State of magnetization

These are weekly magnetized in a direction opposite to that of applied magnetic field

These get weekly magnetized in the direction of applied magnetic field

These get strongly magnetized in the direction of applied magnetic field

When the material in the form of liquid is filled in the U-tube and placed between pole pieces.

Liquid level in that limb goes depressed

Liquid level in that limb arises up

Liquid level in that limb arises up very much

On placing the gaseous materials between pole pieces

The gas expands at right angles to the magnetic field.

The gas expands in the direction of magnetic field.

The gas rapidly expands in the direction of magnetic field

The value of magnetic induction B

B < B₀

B > B₀

B >> B₀

Magnetic susceptibility c

Low and negative |X| » 1

Low but positive X » 1

Positive and high X » 10²

Dependence of c on temperature

Does not depend on temperature (except Bi at low temperature)

Inversely proportional to temperature x∝1/T or x=C/T This is called Curie law, where C = Curie constant

x∝1/T-T_c or x=C/T-T_c  This is called Curie Weiss law.

T_c = Curie temperature

Dependence of c on H

Does not depend independent

Does not depend independent

Does not depend independent

Relative

permeability (m_r)

μ_r < 1

μ_r > 1

μ_r >> 1

m_r = 10²

Intensity of magnetization (I)

I is in a direction opposite to that of H and its value is very low

I is in the direction of H but value is low

I is in the direction of H and value is very high.

I-H curves

Magnetic moment (M)

The value of M is very low (» 0 and is in a direction opposite to H.)

The value of M is very low and is in the direction of H

The value of M is very high and is in the direction of H

Transition of substances (at Curie temperature)

These do not change.

On cooling, these get converted to ferromagnetic materials at Curie temperature

These get changed into paramagnetic materials above Curie temperature

The property of magnetism

Diamagnetism is found in those materials the atoms of which have even number electrons

Para magnetism is found in those materials the atoms of which have majority of electron spins in the same direction

Ferro-magnetism is found in those materials which when placed in an external magnetic field are strongly magnetized

Examples

Cu, Ag, Au, Zn, Bi, Sb, NaCl, H₂O air and diamond etc.

Al, Mn, Pt, Na, CuCl₂, O₂ and crown glass

Ni, Co, Fe, Fe₃O_4, Cd etc.