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)Am^(-1)`
B. `(2)/(3)Am ^(-1)`
C. `6Am^(-1)`
D. `2.4Am^(-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)=8Am^(-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)=8xx(1)/(12)=(2)/(3)Am^(-1)`