Question

A small bar magnet has a magnetic moment $1.2A-m^2$. The magnetic field at a distance 0.1 m on its axis will be: $({\mu }_0=4\pi \times {10}^{-7}T-m/A)$

• A. $1.2\times {10}^{-4}T$
• B. $2.4\times {10}^{-4}T$
• C. $2.4\times {10}^{4}T$
• D. $1.2\times {10}^{4}T$

Answer 1

The correct option is B $2.4\times {10}^{-4}T$

$B=\frac{{\mu }_0}{4\pi }.\frac{2M}{d^3}\Rightarrow B={10}^{-7}\times \frac{2\times 1.2}{(0.1{)}^3}=2.4\times {10}^{-4}T$