A paramagnetic sample shows a net magnetisation of `8Am^-1` when placed in an external magnetic field of `0*6T` at a temperature of `4K`. When the same sample is placed in an external magnetic field of `0*2T` at a temperature of `16K`, the magnetisation will be

Options

A. `(32)/(3) A m^(-1)`
B. `(2)/(3) A m^(-1)`
C. `6 A m^(-1)`
D. `2.4 A m^(-1)`

Answer

B

Explanation

As Curie law explains, we can deduce a formula for the relation between magnetic field induction, temperature and magnetisation.
i.e., I (magnetisation) `prop ("B (magnetic field induction)")/(t ("temperature in kelvin"))`
`rArr (I_(2))/(I_(1))= (B_(2))/(B_(1)) xx (t_(1))/(t_(2))`
Let us suppose, here `I_(1)= 8 A m^(-1)`
`B_(1)= 0.6T, t_(1)= 4K`
`B_(2)= 0.2T, t_(2)= 16K`
`I_(2)`=?
`rArr (0.2)/(0.6) xx (4)/(16) = (I_(2))/(8) rArr I_(2)= 8 xx (1)/(12) = (2)/(3) A m^(-1)`