Question

A bar Magnet of Magnetic Moment 3.0 amp.m${}^2$ is placed in a uniform Magnetic induction field 2 x 10${}^{-5}$ T. If each pole of the magnet experience a force of 6 x 10${}^{-4}$ N, the length of the magnet is

• A. 05 m
• B. 0.3 m
• C. 0.2 m
• D. 0.1 m

Answer 1

Answer: (D)

0.1 m

$M=3A{M}^2$
$M=2\times {10}^{-5}T$
$F=6\times {10}^{-4}N$
$P=Polestrength$
$F=MP$
$6\times {10}^{-4}=2\times {10}^5\times p$
$P=30Am$

$N=pl$
$3=30\times l$
$e=0.1m$