When a coil is rotated in such a way that there is a change in Area perpendicular to the magnetic field , there will be change in magnetic flux that will produced induced emf. The equation in general is E = NBAw sinwt. The maximum induced emf Eo= NBAw. Since this is sinuisoidal the rms voltage can be found .
The position of the coil when the emf is a max is when the flux is zero. At this location the plane of coil is parallel to B.
