Force between two identical bar magnets whose centre are ‘r ’ meter apart is 6.4 N. When their axis are in the same line. If the separation is increased to ‘2r ’ meter, the force between them is reduced to

Two bar magnets placed along same axis/line at distance ‘r ’(between their centers) exert a force on each otherF=μo4π6M1M2r4∴F∝M1M2r4        Where M1&M2 are magnetic moments.⇒F1F2=r2r14 ⇒F2=F1r1r24 ⇒F2=6.4116=0.4 N .