The magnetic flux through a circuit of resistance R changes by an amount $$\Delta $$$$\phi $$ in a time $$\Delta $$t. Then the total quantity of electric charge Q that passes any point in the circuit during the time $$\Delta $$t is represented by

For a coil having L = 2 mH, current flow through it is $$I = {t^2}{e^{ - t}}$$ then, the time at which emf become zero