  We theoretically investigate the transport and magnetotransport properties of
three-dimensional Weyl semimetals. Using the RPA-Boltzmann transport scattering
theory for electrons scattering off randomly distributed charged impurities,
together with an effective medium theory to average over the resulting
spatially inhomogeneous carrier density, we smoothly connect our results for
the minimum conductivity near the Weyl point with known results for the
conductivity at high carrier density. In the presence of a non-quantizing
magnetic field, we predict that for both high and low carrier densities, Weyl
semimetals show a transition from quadratic magnetoresistance (MR) at low
magnetic fields to linear MR at high magnetic fields, and that the magnitude of
the MR > 10 for realistic parameters. Our results are in quantitative agreement
with recent unexpected experimental observations on the mixed-chalcogenide
compound TlBiSSe.
