Question

A $25\, cm$ long solenoid has radius $2\, cm$ and $500$ total number of turns. It carries a current of $15\, A$. If it is equivalent to a magnet of the same size and magnetization $|\bar{M}|$ (magnetic moment/volume), then $|\bar{M}|$ is :

• A. $3 \pi Am^{-1}$
• B. $30000 \,Am^{-1}$
• C. $300\, Am^{-1}$
• D. $30000 \, \pi Am^{-1}$

Answer 1

Answer: (B)

$|\bar{M}|=\frac{\text { Total magnetic moment }}{\text { volume }}$
$=\frac{\text { NiA }}{A l}=\frac{N i}{l}=\frac{500 \times 15}{0.25}=30,000\, Am ^{-1}$