Magnetism self_evaluation_test_magnetism_and_matter Question 19

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

Options:

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:

Correct Answer: A

Solution:

[a] $ F=\frac{{\mu_{0}}}{4\pi }\frac{m_{1}m_{2}}{r^{2}}={{10}^{-7}}\times \frac{30\times 60}{{{(0.3)}^{2}}}=2\times {{10}^{-3}},N $