what is the work done by magnetic force of a magnet on another (permanent) magnet in displacing it through a distance d? assume whatever have to suppose such as their magnetic field B1 & B2 etc. Plz xpln.

force between two magnetic charges is given by F= km1m2/r²             

here k is constant  whose value is u/4pi,m1,m1 are magnitudes of magnetic moment of bar magnet..

if two magnetic charges of same polarity means north towards north are placed then they repel by F amount of force ...

now work done in moving a magnetic charge m is F.dr

  W=F.dr

   W =Fdrcos@ or Fdr        if force is in the direction of displacement

  W =-km1m2/r ........