A circular loop of length $L_o$ is made of wire with cross-sectional area $a_o$. The wire has a resistivity of $\rho_o$. The loop is in a spatially uniform magnetic field. Initially, the loop is orientated such that the normal to its area is perpendicular to the direction of the magnetic field.
The loop is subsequently rotated $90^o$ to an orientation where the normal to its area is parallel to the magnetic field direction. During the time the loop is rotating, and charge of $Q_o$ flows in the wire.
What is the magnitude of the magnetic field in which the loop is placed?