The force between two magnet poles separated by a distance 'd' in air is 'F'. At what distance between them does the force become doubled ?

The force between two similar charges of magnitude 2C each separated by a distance 2km

What is the distance between pole and focal point called ?

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.