Question

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

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

Answer 1

Answer: (B)

$3.0$

$I=\frac{M}{V}$
$=\frac{M}{mass/density}$
Given, $mass=1g={10}^{-3}kg$
and $density=5g/{cm}^3$
$=\frac{5\times {10}^{-3}}{{\left({10}^{-2}\right)}^5}$
$=5\times {10}^{3}kg/m^3$
$I=\frac{6\times {10}^{-7}\times 5\times {10}^3}{{10}^{-3}}=3$