Diamagnetic effects occurs in materials where magnetic field due to electronic motions i.e orbiting and spinning completely cancels each other
Thus for diamagnetic materials intrinsic magnetic moments of all the atoms is zero and such materials are weakly affected by the magnetic field
The diamagnetic effects in material is a result of inductive action of the externally applied field on the molecular currents
To explain the occurrence of this effect ,we first consider the Lenz law accordingly to which, whenever there is a change in a flux in a circuit, an induced current is setup to oppose the change in flux linked by the circuit
Here the circuit under consideration is orbiting electrons in an atom, ions or molecules constituting the material under consideration
we know that moving electron are equivalent to current and when there is a current ,there is a flux
On application of external field ,the current changes to oppose the change in flux and this appear as a change in the frequency of the revolution
The change in frequency gives rise to magnetization as a result of which each atom will get additional magnetic moment ,aligned opposite to the external field causing it
it is this additional magnetic moment which gives diamagnetic susceptibility a negative sign which is order of 10-5 for most diamagnetic material (e g. bismith,lead,copper,silicon,diamond etc)
All substances are diamagnetic ,although diamagnetism may vary frequently be masked by a stronger positive paramagnetic effect on the part of external magnetic field and as a result of internal interactions
Diamagnetic susceptibility is independent of temperature as effect of thermal motion is very less on electron orbits as long as it deform them
