Question

Two short bar magnets each of magnetic moment $10A{m}^2$ are kept at the two opposite corners of a square of side 1m with magnetic moments parallel. The field strength at any one of the other corners is :

• A. $1\times {10}^{-6}T$
• B. $2\times {10}^{-6}T$
• C. $3\times {10}^{-6}T$
• D. $4\times {10}^{-6}T$

Answer 1

The correct option is A $1\times {10}^{-6}T$

$B_1=\frac{2{\mu }_{0}M}{4\pi d^3}$

$B_2=\frac{-{\mu }_{0}M}{4\pi d^3}$

$B=B_1+B_2$

$=\frac{{10}^{-7}\times 10}{1^3}\times 1$

$=1\times {10}^{-6}$ T