Question

The magnetic moment of a magnet of length $10 \,cm$ and pole strength $4.0\, Am$ will be:

• A. $0.4\,A{{m}^{2}}$
• B. $1.6\,A{{m}^{2}}$
• C. $20\,A{{m}^{2}}$
• D. $8.0\,A{{m}^{2}}$

Answer 1

Answer: (A)

$0.4\,A{{m}^{2}}$

Answer 2

The magnetic moment or magnetic dipole moment is a measure of the strength of a magnetic source. The magnetic moment is denned as pole strength multiplied by the distance between the poles,
$M=m\times 2l$
Given, $2l=10\,cm=10\times {{10}^{-2}}m,\,m=4\,A-m$
$\therefore$ $M=0.10\times 4=0.4\,A-{{m}^{2}}$
Note: Magnetic moment is a vector quantity pointing along the axis of the magnet from $S$ to $N$.