Question

Two small magnets each of magnetic moment 10 $Am^2$ are placed in end on position 0.1 m apart from their centres. The force acting between them is

• A. $0.6\times10^7N$
• B. $0.06\times10^7N$
• C. $0.6\,N$
• D. $0.06 \,N$

Answer 1

Answer: (C)

$0.6\,N$

Answer 2

Magnetic force, $F =\frac{\mu_0}{4\pi}\frac{6M_1 M_2}{r^4}$
$F = 10^{-7}\times\frac{6\times10\times10}{(0.1)^4}$
$F=\frac{600\times10^{-7}}{0.0001}$
$F=0.6N$