Question

A bar magnet has a pole of 48 ampere-meter which are 25cm apart. What is the magnetic moment of the magnet?
$\begin{align}
  & a)12A{{m}^{2}} \\
 & b)6A{{m}^{2}} \\
 & c)6{}^{A}/{}_{{{m}^{2}}} \\
 & d)12{}^{A}/{}_{{{m}^{2}}} \\
\end{align}$

Answer 1

Hint : First of all to solve the question we must know what is the magnetic moment. We can define the magnetic moment as the property of the magnet that interacts with a field. The magnetic moment is also called the magnetic dipole moment. That refers to the strength of the magnetic field and its orientation.

Complete step-by-step solution:
Given that,
\[m=48Am\]
$L=25cm$
Then the magnetic moment M is given by the equation,
$M=m\times L$…………(1)
Where m is the pole strength of the magnet
L is the length of the magnet
Thus by substituting the values in the above equation we get,
$M=48\times 25\times {{10}^{-2}}$
$M=12A{{m}^{2}}$
Therefore option (d) is correct.

Note: Also remember that the magnetic moment is a vector quantity. This quantity determines the force that the magnet can exert on some electric currents and the torque that will exert on it. The magnetic moment has the direction that points from the south to north pole of a magnet.