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 $\frac{M}{4}$
• C. Magnetic moment $\frac{M}{2}$
• D. Magnetic moment M

Answer 1

Answer: (C)

Magnetic moment $\frac{M}{2}$

If pole strength, magnetic moment and length of each part are m', M' and L' respectively then

$m^{{}^{\prime }}=\frac{m}{2}$ $m^{{}^{\prime }}=m$
$L^{{}^{\prime }}=L$ $L^{{}^{\prime }}=\frac{L}{2}$
$\Rightarrow M^{{}^{\prime }}=\frac{M}{2}$ $\Rightarrow M^{{}^{\prime }}=\frac{M}{2}$