Question

A rod of ferromagnetic material with dimensions $10cm\times 0.5cm\times 0.2cm$ is placed in a magnetic field of strength $0.5\times 10^{4}A{m}^{-1}$ as a result of which a magnetic moment of $5A{m}^2$ is produced in the rod. The value of magnetic induction will be :-

• A. $0.54T$
• B. $6.28T$
• C. $0.358T$
• D. $2.591T$

Answer 1

Answer: (B)

Volume of $=10\times 0.5\times 0.2\times 10^{-6}=10^{-6}{m}^3$
$H=0.5\times 10^{4}A{m}^{-1},M=5A{m}^{2}B=?$
Intensity of magnetisation i.e.
$I=\frac{M}{V}=\frac{5}{10^{-6}}=5\times 10^{6}Am$
From $B={\left(\mu \right)}_0\left(I+H\right)$
Magnetic induction
i.e. $B=4\pi \times 10^{-7}\left[5\times 10^6+0.5\times 10^4\right]$
$=4\pi \times 10^{-7}\times 5\times 10^6=20\times 3.14\times 10^{-1}$
$=6.28T$