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A bar magnet M is dropped so that is falls vertically through the coil C. The graph obtained for voltage produced across the coil Vs time is shown in figure. (i) Explain the shape of the graph. (ii) Why is the negative peak longer than the positive peak ? |
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Answer» Solution :(i) When the bar magnet moves towards the coil magnetic flux passing through the coil INCREASES as velocity of magnet increases in downward DIRECTION, e.m.f. induced also increases, DUE to formation of similar pole repulsive FORCE decreases the rate of increase of flux. (ii) once the magnet has passed through the coil, flux decreases in downward direction but `(d phi)/(dt)` increases as self induced e.m.f. in the coil maintains its flux in the same direction. Thus due to the addition of self induced e.m.f. in same direction according to LENZ’s law. |
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