Question

A bar magnet of pole strength $2\times {10}^{-2}A-m$ has its effective length $8$ cm. What is its magnetic moment?

• A. $16\times {10}^{-4}A-m$
• B. $1.6\times {10}^{-3}A-m^2$
• C. $16mA-m^2$
• D. $16\times {10}^{-3}A-m$

Answer 1

The correct option is B

$1.6\times {10}^{-3}A-m^2$

Step 1: Given data

Pole strength of bar magnet $=$$2\times {10}^{-2}A-m$

Distance between poles $=$ $8$ cm

Step 2: Finding a magnetic moment

We know that magnetic moment is given by Pole strength multiplied by the distance between poles.

Substituting values we get,

Magnetic moment $=$$2\times {10}^{-2}\times 8$

$=16\times {10}^{-2}$

$=1.6\times {10}^{-3}A-m^2$

Hence, the magnetic moment is $1.6\times {10}^{-3}A-m^2$.

The correct option is (B).