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JEE Mains · Physics · STD 12 - Moving charges and magnetism
  • JEE Mains 2020
  • Hard
  • MCQ

A wire carrying current \(I\) is bent in the shape \(A\,B\,C\,D\,E\,F\,A\) as shown, where rectangle \(A\,B\,C\,D\,A\) and \(A\,D\,E\,F\,A\) are perpendicular to each other. If the sides of the rectangles are of lengths \(a\) and \(b,\) then the magnitude and direction of magnetic moment of the loop \(A\,B\,C\,D\,E\,F\,A\,\) is

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Verified Solution

Answer & Solution

Correct Answer

(A) \(\sqrt{2}\) \(abI\), along \(\left(\frac{\hat{j}}{\sqrt{2}}+\frac{\hat{ k }}{\sqrt{2}}\right)\)

Step-by-step Solution

Detailed explanation

Sol. \(\quad M=N I A\)

\(N =1\)

For \(ABCD\)

\(\overrightarrow{ M }_{1}= abI \hat{ K }\)

For \(DEFA\)

\(\overrightarrow{ M }_{2}= abI \hat{ j }\)

\(\overrightarrow{ M }=\overrightarrow{ M }_{1}+\overrightarrow{ M }_{2}\)

\(=\operatorname{ab} I (\hat{ k }+\hat{j})\)

\(=\operatorname{ab} I \sqrt{2}\left(\frac{\hat{j}}{\sqrt{2}}+\frac{\hat{ k }}{\sqrt{2}}\right)\)