In this post, we have solved physics numerical on the magnetic moment. This is good for class 12. The magnetic moment formula is used. refer: Magnetic moment formula
Question 1] A bar magnet is placed flat on a flat table, with an applied magnetic field moving upwards through the table, meaning the field is perpendicular to the bar magnet. The magnetic field strength is B = 1 T, if this causes the magnet to experience a torque of τ=4×10−3Nm what is the magnet’s magnetic moment?
If the magnetic field is perpendicular to the bar magnet, sin(θ)=1 and meaning that the magnetic moment is given by m = Torque/Magnetic field strength = τ /B ……………… 
and, B = 1 T
m = τ /B = 4×10−3 / 1 = 4×10−3 Am2
Magnetic moment formula – check this post, if you want to check the magnetic moment formula.