  If a magnetically dominated magnetosphere is to extract a black hole's
rotational energy and transmit it to distant regions, then the inner light
surface of that magnetosphere must lie within the ergoregion. That inner light
surface condition limits the angular velocity of magnetic field lines. We take
the distribution of magnetic field line angular velocity on the horizon to be a
useful proxy for inner light surface location and study how different
distributions affect the structure of energy-extracting magnetospheres. Within
magnetospheres that exhibit differential field line bending towards both the
azimuthal axis and the equatorial plane, we find that the total Poynting flux
energy directed outward along the azimuthal axis can vary by over a factor of
100 for a single value of black hole spin.
