Question

Question #68dbe

Answer 1

Force of attraction `F` between two magnetic poles `q_(m_1) and q_( m_2)` which can be considered as point masses is given by

`F = (mu\ q_(m_1)\ q_( m_2)) /(4 π r ^2)`
where `mu` is the permeability of the intervening medium and `r` is their separation.

Taking `mu=mu_0` permeability of free space `= 4pi × 10^-7\ H` and inserting given values we get

`10^-2= (4pi × 10^-7xx300xx40) /(4 π r ^2)`
`r= sqrt(( 10^-7xx300xx40) /( 10^-2))`
`r= 0.35\ m`