A Possible Means for Making an Airplane Radar-Invisible Is to Coat

Multiple Choice

A possible means for making an airplane radar-invisible is to coat the plane with an antireflective polymer.If radar waves have a wavelength of 3.84 cm,and the index of refraction of the polymer is n = 1.6,how thick would the coating be if a 180° phase change occurs at both surfaces?

A) 24 mm
B) 7.5 mm
C) 32 mm
D) 6.0 mm