InterviewSolution
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InterviewSolution
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A conducing circular loop is placed in a uniform magnetic field of indution `B` tesla with its plane normal to the field. Now, radius of the loop starts shrinking at the rate `(dr//dt)`. Then the induced e.m.f. at the instant when the radius is `r` is:A. `pi r B ((dr)/(dt))`B. `2 pi r B ((dr)/(dt))`C. `pi r^(2) ((dr)/(dt))`D. `((pi r^(2))/(2))^(2) ((dt)/(dt))` |
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Answer» Correct Answer - B Here: `A = pi r^(2)`, and `phi = BA = B pi r^(2)` As `e = (d phi)/(dt) = (d)/(dt) (B pi r^(2)) = pi B (2 r) (dr)/(dt)` `= 2 pi r B (dr)/(dt)` |
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