Question

A magnetic induction due to a short bar magnetic of magnetic moment $5.4A{m}^2$ at a distance of $30cm$ on the equatorial line is

• A. $2\times {10}^{-4}T$
• B. $2\times {10}^{-5}T$
• C. $3\times {10}^{-5}T$
• D. $3\times {10}^{-4}T$

Answer 1

Answer: (B)

$2\times {10}^{-5}T$

Given

$M=5.4A{m}^2$

$r=30cm=0.3m$

$B=?$

A magnetic induction due to a short bar magnet on the equatorial line is given by

$B=\frac{{\mu }_0}{4\pi }\times \frac{M}{r^3}$

$B={10}^{-7}\times \frac{5.4}{{0.3}^2}={10}^{-7}\times \frac{5.4}{0.027}={10}^{-7}\times 200=2\times {10}^{-5}Tesla$