A magnetized steel wire $31.4\;cm$ long has pole strength of $0.2 \;Am$ It is then bent in the form of a semicircle. Calculate the magnetic moment of the needle.

Question

$\begin{array}{1 1} 0.4 \;Am^2 \\ 0.04 \;Am^2 \\ 0.4 \;A/m^2 \\ 0.04 \;A/m^2 \end{array} $