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. `pi r^(2)((dB)/(dt))`C. `2pi rB((dr)/(dt))`D. `((pir^2)/(2))^(2)B cdot(dr)/(dt)` |
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Answer» Correct Answer - C Area of the coil = `pi r^(2)` `|e| = (d phi)/(dt)=d/(dt)[AB]` `=d/(dt)[pir^(2)B] = pi B d/(dt)[r^2]` `pi B 2r (dr)/(dt) = 2 pi r B((dr)/(dt))`. |
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