CBSE Class 12-science Answered
Susceptibility is a measure of the ease with which a substance can be magnetized.
It is a quantitative measure of the extent to which a material may be magnetized on applying a given applied magnetic field. The magnetic susceptibility of a material, commonly symbolized by Χ, is equal to the ratio of the magnetization M within the material to the applied magnetic field strength H, or Χ = M/H.
Coercivity is a measure of the reverse magnetic field required to completely demagnetize a substance that has been fully magnetized. A permanent magnet is more difficult to demagnetise than a temporary magnet. So the coercivity of a 'hard 'or permanent magnet is higher than that of a soft or temporary magnet.
The strength of the magnetic field required to completely demagnetise a material is the measure of its coercivity. Its unit will A/m. Coercivity can be better understood by looking at the hysterisis loop. The value of H where the loop cuts the x axis when the direction of current is reversed is the value of coercivity.