Question

The period of oscillation of a bar magnet in a vibration magnetometer is $2\, \sec$. The period (in $\sec$) of oscillation of a bar magnet whose magnetic moment is $4$ times that of $1$st magnet is -

Answer 1

$\frac{ T _{2}}{ T _{1}}=\sqrt{\frac{ M _{1}}{ M _{2}}}=\sqrt{\frac{ M _{1}}{4 M _{1}}}$
$T _{2}=\frac{2}{2}=1\, \sec$