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(B) According to Faraday's law of electromagnetic induction,the induced $emf$ is given by $e = -\frac{d\phi}{dt}$.In the first case,the magnet moves t

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$2e$

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(B) According to Faraday's law of electromagnetic induction,the induced $emf$ is given by $e = -\frac{d\phi}{dt}$.In the first case,the magnet moves towards the stationary coil with speed $v$. The rate of change of magnetic flux is proportional to the relative velocity,so $e \propto v$.In the second case,both the magnet and the coil move away from each other with speed $v$. The relative velocity between them is $v_{rel} = v - (-v) = 2v$.Since the induced $emf$ is directly proportional to the relative velocity between the magnet and the coil,the new induced $emf$ will be $e' \propto 2v$.Therefore,$e' = 2e$.

In the given figure,the magnet is moved towards the coil with speed $v$ and the induced $emf$ is $e$. If the magnet and the coil recede away from one another,each moving with speed $v$,the induced $emf$ in the coil will be

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