Question

The magnetic moment of a bar magnet is $3.6\times 10^{-3}A.m^2$ .Its pole strength is 120 milli amp. m. Its magnetic length is

• A. 3cm
• B. 0.3cm
• C. 33.33cm
• D. $3\times 10^{-2}cm$

Answer 1

Answer: (A)

For a bar magnet, the magnetic moment is
$M=polestrength\times magneticlength$
So the magnetic length will be
$l_{mag}=\frac{M}{m}$
$\Rightarrow l_{mag}=\frac{3.6\times 10^{-3}}{120\times 10^{-3}}=3\times 10^{-2}m=3cm$