A plane electromagnetic wave is incident normally on the surface of a conducting fluid of large but finite conductivity (σ), immersed in a uniform magnetic field B₀ such that k ⊥ B₀ . Assume that the magnetic field (B) of the incoming wave is parallel to B₀. Show that there are two wave modes that penetrate the fluid. One of them is an unattenuated magnetosonic wave and the other one is a mode that has an effective skin depth δ = (V_s/V_m) δ_rc, where V_s and V_m are the sound and magnetosonic velocities, respectively, and δ_rc is the skin depth in a rigid conductor.