Force between two identical bar magnets whose centres are r metre apart is 4.8 N, when their axes are in the same line. If separation is increased to 2 r, the force between them is reduced to

Question

Force between two identical bar magnets whose centres are r metre apart is 4.8 N, when their axes are in the same line. If separation is increased to 2 r, the force between them is reduced to (A) 2.4 N (B) 1.2 N (C) 0.6 N (D) 0.3 N

Tardigrade Admin · Accepted Answer

In magnetic dipole, force propto (1/r4) Hence, new force =(4.8/24)=(4.8/16)=0.3 N

Q. Force between two identical bar magnets whose centres are $r$ metre apart is $4.8 N$ , when their axes are in the same line. If separation is increased to $2 r$ , the force between them is reduced to

2.4 N

1.2 N

0.6 N

0.3 N

In magnetic dipole, force $\propto \frac{1}{r ^{4}}$
Hence, new force $= \frac{4.8}{2 ^{4}} = \frac{4.8}{16} = 0.3 N$

Q. Force between two identical bar magnets whose centres are r metre apart is 4.8N, when their axes are in the same line. If separation is increased to 2r, the force between them is reduced to