Two magnetic poles of strengths 40Am and 10 Am are separated by a distance of 20 cm in air. Find the force between them. If the distance is reduced to 10 cm, find the force.

Explanation

i) Pole strength of magnetic poles ,
`m_1 = 40 Am and m_2= 10 Am`
Distance between the poles , ` d=20 cm = 0.2 m`
Force between the magnetic poles ,` (mu_0)/(4pi)(m_1m_2)/(d^(2))`
`= (4 pi xx 10^(-7))/(4pi ) xx (40 xx 10)/((0.2)^(2)) = 10^(-3) N`
ii) Distance between the poles , `d^(1) = 10 cm = 0.1 m`
Forece between the magnetic poles .
`F^(1) = (mu_0)/(4pi)(m_1 m_2)/((d^1)^(2))`
`= ( 4pi xx 10^(-7))/(4 pi ) xx (40 xx 10)/( (0.1)^(2)) = 4 xx 10^(-3)N`.