For 10 points, name this complex quantity whose imaginary part is reactance and whose real part is resistance.
For fields outside a good conductor, approximate boundary conditions named for this quantity are that E equals the normal vector cross H times this quantity at the surface. The transverse magnetic field in a waveguide is equal to the direction of propagation cross the transverse electric field over this quantity. This value is equal to the square root of the permittivity over permeability, and for free space it's equal to about (*) 377 of a certain unit. When this quantity for a load is equal to the complex conjugate of this quantity for the source, power transfer to the load will be maximal. For an inductor it's i times frequency times inductance and for a capacitor it's one over i times frequency times capacitance. For 10 points, name this complex quantity whose imaginary part is reactance and whose real part is resistance. 
For fields outside a good conductor, approximate boundary conditions named for this quantity are that E equals the normal vector cross H times this quantity at the surface.
impedance [prompt on "resistance"] 