Two identical coaxial circular coils, each of radius $R$ and $N$ turns, are placed a distance $d$ apart, where $d << R$. A current $I$ flows through both coils in the same direction. A small circular loop of radius $r$ ($r << R$) and resistance $\rho$ is placed coaxially midway between the coils. If the current in the larger coils is now varied at a rate of $\frac{dI}{dt}$, what is the induced current in the small loop?

The induced emf of a generator when the flux of poles is doubled and speed is doubled