Question

A paramagnetic sample shows a net magnetisation of 8 Am’1 when placed in an external magnetic field of 0.6 T at a temperature of 4 K. When the same sample is placed in an external magnetic field of 0.2 T at a temperature of 16 K, the magnetisation will be

• A.
• B.
• C. 6 A m-1
• D. 2.4 A m-1

Answer 1

Answer: (B)

Answer 2

Here

$\mathrm { M } _ { 1 } = 8 \mathrm { Am } ^ { - 1 } , \mathrm {~B} _ { 1 } = 0.6 \mathrm {~T} , \mathrm {~T} _ { 1 } = 4 \mathrm { k } , \mathrm { B } _ { 2 } = 0.2 \mathrm {~T} , \mathrm {~T} _ { 2 } = 16 \mathrm {~K}$then, for paramagnetic materials

Magnetization (M) (Curie’s law)

Now, in the first case, $\mathrm { M } _ { 1 } = \frac { \mathrm { CB } _ { 1 } } { \mathrm {~T} _ { 1 } }$ ….. (i)

And in the second case ….. (ii)

Dividing equation (i) by (ii), we get

$\mathrm { M } _ { 2 } = \frac { 8 } { 12 } = \frac { 2 } { 3 } \mathrm { Am } ^ { - 1 }$