A coil having effective area $A$, is held with its plane normal to magnetic field of induction $B$. The magnetic induction is quickly reduced by $25%$ of its initial value in $2$ second. Then the e.m.f. induced across the coil will be
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Induced EMF is directly proportional to the rate of change of magnetic flux. Use $e = \frac{\Delta \phi}{\Delta t}$ to find the average induced EMF.