$A$ steel wire of length $\ell$ has a magnetic moment $M$. It is then bent into a semicircular arc. The new magnetic moment is

What is the magnitude of the equatorial and axial fields due to a bar magnet of length $5.0 \; cm$ at a distance of $50 \; cm$ from its mid-point? The magnetic moment of the bar magnet is $0.40 \; A m^{2}$.

$A$ cylindrical rod magnet has a length of $5 \, cm$ and a diameter of $1 \, cm$. It has a uniform magnetization of $5.30 \times 10^3 \, A/m$. What is its magnetic dipole moment?

$A$ bar magnet of magnetic moment $3.0 \, A-m^2$ is placed in a uniform magnetic induction field of $2 \times 10^{-5} \, T$. If each pole of the magnet experiences a force of $6 \times 10^{-4} \, N$,the length of the magnet is.....$m$

Write a brief history of magnets.

The time period of a freely suspended magnet is $4 \ s$. If it is broken in length into two equal parts and one part is suspended in the same way,then its time period will be: (in $s$)