Question

The magnetic dipole of a bar magnet of geometric length $18cm$ and pole strength $100Am$ is:

• A. $15A{m}^2$
• B. $18A{m}^2$
• C. $9A{m}^2$
• D. $7.5A{m}^2$

Answer 1

The correct option is A $15A{m}^2$

Magnetic dipole of a bar magnet

$=m\times 2l$

$magnetic-length\left(2l\right)=\frac{5}{6}geometric-length$

$2l=\frac{5}{6}\times 18=15cm=0.15m$

$=m\times 2l$

$=100\times 0.15$

$=15A{m}^2$