Question

The mass of iron rod is 110 gm, its magnetic moment is 20 Am${}^2$. The density of iron is 8gm/ cm${}^3$. The intensity of magnetization is nearly

• A. $2\times {10}^{5}A{m}^{-1}$
• B. $2.26\times {10}^{6}A{m}^{-1}$
• C. $1.6\times {10}^{6}A{m}^{-1}$
• D. $1.4\times {10}^{6}A{m}^{-1}$

Answer 1

The correct option is D $1.4\times {10}^{6}A{m}^{-1}$

$I=\frac{m}{v}$

$m=20A{m}^2$

$d=\frac{M}{v}$

$v=\frac{M}{d}$

$=\frac{100\times {10}^{-3}}{8000}$

$1.375\times {10}^{-5}$

$I=\frac{20}{1.375\times {10}^{-5}}$

$I=1.454\times {10}^{6}A{m}^{-1}$