A0.5 mhz antenna carried by an airplane flying in air over the ocean generates a plane wave that is normally incident upon the air-water interface. the amplitude of the incident electromagnetic wave is 3 (kv/m). the airplane is trying to communicate with a submarine which is submerged below the ocean surface. the submarine's receiver requires a minimum signal amplitude of 0.01 (mu v/m). ocean water has the following material properties epsilon _r = 81 mu _r =1 sigma = 5 s/m from this information, what is the maximum depth d of the submarine for which successful communication is possible?