Question

In the figure, AB is a long straight wire carrying a current of 20A and CDFG is a rectangular loop of size 20 cm x 9cm carrying a current of 10A. The edge CG is parallel to AB, at a distance of 1cm from it. The force exerted on the loop by the magnetic field of the wire is

• A. $3.6\times {10}^{-4}N$ attraction
• B. $3.6\times {10}^{-4}N$ epulsion
• C. $7.2\times {10}^{-4}N$ attraction
• D. $7.2\times {10}^{-4}N$ repulsion

Answer 1

The correct option is C $7.2\times {10}^{-4}N$ attraction

$F=\frac{{\mu }_0{i}_1{i}_{2}l}{2\pi }[\frac{1}{r_1}-\frac{1}{r_2}]=2\times {10}^{-7}\times 20\times 10\times 0.2[\frac{1}{{10}^{-2}}-\frac{1}{10\times {10}^{-2}}]=8\times {10}^{-6}\times \left[\frac{9}{10}\right]\times {10}^2=7.2\times {10}^{-4}N$