InterviewSolution
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InterviewSolution
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A wire of length `L` is shaped into a circle and then folded as shown. Magnetic moment of the frame when a current `i` is passed through it is: A. `(L^(2)i)/(4pi)`B. `(L^(2)i)/(4sqrt2pi)`C. `(L^(2)i)/(4)`D. `(L^(2)i)/(8pi)` |
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Answer» Correct Answer - B Since `L=2pir, r=(L)/(2pi)` Area of circle `pir^(2)=(piL^(2))/(4pi^(2))=(L^(2))/(4pi)` Area of each half of circle `=(L^(2))/(8pi)` Magnetic moment of each half `=(L^(2)i)/(8pi)` The two magnetic moments are at right angles to each other. Magnetic moment of the frame `=sqrt(((L^(2)i)/(8pi))^(2)+((L^(2)i)/(8pi))^(2))=(sqrt2.L^(2)i)/(8pi)=(L^(2)i)/(4sqrt(2pi))` |
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