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Magnetism And Matter

Question
CBSEENPH12037797

Define magnetic susceptibility of a material. Name two elements, one having positive susceptibility and the other having negative susceptibility. What does negative susceptibility signify?

Solution
Magnetic susceptibility of a material is defined as the ratio of the intensity of magnetisation (I) induced in the material to the magnetisation force (H) applied on it.

Magnetic susceptibility is given by 

χm = IH 

Diamagnetic substances like copper, lead etc., has negative susceptibility. 
Paramagnetic substances like aluminium, calcium etc., has positive susceptibility. 

If the value of susceptibilty for a substance is negative, then it is a diamagnetic substance and the magnetic character is lost when kept in an external magnetic field. Negative susceptibility of diamagnetic substance is independent of temperature.