A conducting disc of radius $R$ rotating at angular velocity $\omega$ in a perpendicular uniform field $B$: EMF between center and rim $= B\omega R^2/2$. This is a continuous DC generator (no alternation). Each radial element of the disc acts like a rotating rod. Current flows from center to rim (or vice versa) through an external circuit connected via sliding contacts (brushes). The EMF is independent of the disc material and depends only on $B$, $\omega$, and $R$.