EMI Questions

In which of the following devices, the eddy current effect is not used?

A $800$ turn coil of effective area $0.05{\text{m}}^2$ is kept perpendicular to a magnetic field $5\times 10^{-5}\text{T}$. When the plane of the coil is rotated by $90^{\circ }$ around any of its coplanar axis in $0.1\text{s}$, the emf induced in the coil will be: