Question

Two similar bar magnets $P$ and $Q$, each of magnetic moment $M$, are taken. If $P$ is cut along its axial line and $Q$ is cut along its equatorial line, all the four pieces obtained have

• A. equal pole strength
• B. magnetic moment $M/4$
• C. magnetic moment $M/2$
• D. magnetic moment $M$

Answer 1

Answer: (C)

If pole strength, magnetic moment and length of each part are $m^{\prime },M^{\prime }$ and $L^{\prime }$ respectively then
$\Rightarrow m^{\prime }=\frac{m}{2}$
$\Rightarrow m^{\prime }=m$
$\Rightarrow L^{\prime }=L$
$\Rightarrow L^{\prime }=\frac{L}{2}$
$\Rightarrow M^{\prime }=\frac{M}{2}$
$\Rightarrow M^{\prime }=\frac{M}{2}$