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)

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 $N$.