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A metal bar is moving with a velocity of `v = 5 cm s^(-1)` over a U-shaped conductor. At `t = 0`, the external magnetic field is `0.1 T` direction out of the page and is increasing at a rate of `0.2 T s^(-1)`. Tale `l = 5cm`, and at `t = 0, x = 5 cm`. The current flowing in the circuit isA. (a) `2.5 A`B. (b) `5 A`C. ( c) `1 A`D. (d) `2 A` |
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Answer» Correct Answer - A (a) Let us take anticlockwise direction as positive, then area vector in upward direction will be positive `phi = BA = Blx` `e = -(dphi)/(dt) = -l[B(dx)/(dt) + x(dB)/(dt)]` `= -5 xx 10^(-2)[0.1 xx (-5 xx 10^(-2)) + 5 xx 10^(-2) xx 0.2]` `= -250 xx 10^(-6) V = -250 muV` emf is coming out to be negative, so it should be clockwise. Current: `I = (e)/(R ) = (250 xx 10^(-6))/(10^(-4)) = 2.5 A` |
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