A paramagnetic sample shows a net magnetisation of 8 Am-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 a) 32/3 Am-1 b) 2/3 Am-1 c) 6 Am-1 d) 2.4 Am-1
Correct option is B) Here, M1=8Am−1,B1=0.6T, T1=4K,B2=0.2T,T2=16K Then, for paramagnetic materials, magnetisation(M)=TCB(Curie's law) Now, in the first case, M1=T1CB1 and in the second case, M2=T2CB2 Dividing equation (i) by (ii), we get M2M1=B2B1⋅T1T2⇒M2M1=0.20.6×416 M28=3×4 M2=128=32Am−1.
