  We present models of ohmic heating in the interiors of hot jupiters in which
we decouple the interior and the wind zone by replacing the wind zone with a
boundary temperature Tiso and magnetic field Bphi0. Ohmic heating influences
the contraction of gas giants in two ways: by direct heating within the
convection zone, and by heating outside the convection zone which increases the
effective insulation of the interior. We calculate these effects, and show that
internal ohmic heating is only able to slow the contraction rate of a cooling
gas giant once the planet reaches a critical value of internal entropy. We
determine the age of the gas giant when ohmic heating becomes important as a
function of mass, Tiso and induced Bphi0. With this survey of parameter space
complete, we then adopt the wind zone scalings of Menou (2012) and calculate
the expected evolution of gas giants with different levels of irradiation. We
find that,with this prescription of magnetic drag, it is difficult to inflate
massive planets or those with strong irradiation using ohmic heating, meaning
that we are unable to account for many of the observed hot jupiter radii. This
is in contrast to previous evolutionary models that assumed that a constant
fraction of the irradiation is transformed into ohmic power.
