Two magnetic poles exert a force equal to `2kg` f on each other, when placed at a distance of `4cm` in air. If strength of one pole is eight times the strength of the other pole, what is the strength of stronger pole? (Take `g=10m//s^2`)

Explanation

Here, `F=2kg f=20N`
`r=4cm=4xx10^-2m`
If `m_1=m, m_2=8m=?`
From Gauss's Law in magnetism
`F=(mu_0)/(4pi)(m_1m_2)/(r^2)`
`20=10^-7(mxx8m)/((4xx10^-2)^2)=(8m^2)/(16)xx10^-3`
`m^2=(40)/(10^-3)=4xx10^4`
`m=2xx10^2`
`:.` Strength of stranger pole `=8m`
`=8xx2xx10^2`
`=1600Am`