Savchenko Problem 11.5.8

The key insight is that a rotating superconductor maintains constant magnetic flux through itself—any change in external flux induces a current that exactly cancels it. As the ring rotates, the component of $B$ threading through it oscillates sinusoidally, forcing the induced current to oscillate as well to keep total flux constant. You'll need to find how the flux changes with rotation angle, then use $\Phi_{\text{total}} = \text{constant}$ and $\Phi = LI$ to relate the current amplitude to the geometry and field strength.

The key insight is that a rotating superconductor maintains constant magnetic flux through itself—any change in external flux induces a current that exactly cancels it. As the ring rotates, the component of $B$ threading through it oscillates sinusoidally, forcing the induced current to oscillate as well to keep total flux constant. You'll need to find how the flux changes with rotation angle, then use $\Phi_{\text{total}} = \text{constant}$ and $\Phi = LI$ to relate the current amplitude to the geometry and field strength.