Question

The dipole moment of the short bar magnet is $12.5 \, A-m^2$. The magnetic field on its axis at a distance of $0.5\, m$ from the centre of the magnet is

• A. $1.0 \times 10Z^{-4} \,N/A-m$
• B. $4 \times 10^{-2}\, N/A-m$
• C. $2 \times 10^{-6} \,N/A-m$
• D. $6.64 \times 10^{-8}\, N/A-m$

Answer 1

Answer: (C)

The magnetic field,
$ B = \frac{\mu_{0}}{4\pi}. \frac{2N}{d^{3}} $
$ = 10^{-7} \times\frac{2\times1.25}{\left(0.5\right)^{3}} $
$= 2 \times10^{-6} \,NA-m$