Question

Two isolated point poles of strength $30Am$ and $60Am$ are placed at a distance of $0.3m$. The force of repulsion is:

• A. $2\times {10}^{-3}N$
• B. $2\times {10}^{-4}N$
• C. $2\times {10}^{5}N$
• D. $2\times {10}^{-5}N$

Answer 1

The correct option is A $2\times {10}^{-3}N$

$F=\frac{{\mu }_0}{4\pi }\frac{m_1{m}_2}{r^2}$
$={10}^{-7}\times \frac{30\times 60}{{\left(0.3\right)}^2}$
$=2{\times 10}^{-3}N$