Question

The magnetic moment produced in a substance of 1 g is $6\times {10}^{-7}A-m^2.$ If its density is 5 g $c{m}^{-3},$ then the intensity of magnetisation in A/m will be:

• A. $3.0$
• B. $3\times {10}^{-6}$
• C. $8.3\times {10}^6$
• D. $1.2\times {10}^{-7}$

Answer 1

The correct option is A $3.0$

Intensity of magnetisation,
$l=\frac{M}{V}=\frac{M}{mass/density}$
Given, mass =$1g={10}^{-3}kg$ and density
$=5g/c{m}^3$
$=\frac{5\times {10}^{-3}kg}{({10}^{-2}{)}^3{m}^3}=5\times {10}^{3}kg/m^3$
Hence, $l=\frac{6\times {10}^{-7}\times 5\times {10}^3}{{10}^{-3}}=3A/m$