1. Tardigrade
  2. Question
  3. Physics
  4. The force between two short bar magnets with magnetic moments M1 and M2 whose centres are r metre apart is 0.8 N when their axes are in the same line. If the separation is increased to 2 r, then force between them is reduced to

Question Error Report

Thank you for reporting, we will resolve it shortly

Back to Question

Q. The force between two short bar magnets with magnetic moments $M_{1}$ and $M_{2}$ whose centres are $r$ metre apart is $0.8\, N$ when their axes are in the same line. If the separation is increased to $2\, r$, then force between them is reduced to

Magnetism and Matter

Solution:

$F=\frac{\mu_{0}}{4 \pi} \cdot \frac{6 M_{1} M_{2}}{r^{4}}$
i.e., $\propto \frac{1}{r^{4}} $
$\therefore F'=\frac{F}{16}=\frac{8}{16}=0.5 \,N$