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 6.00 cm,and the index of refraction of the polymer is n = 1.68,how thick would the coating be if a 180° phase change occurs at both surfaces?
A)17.9 mm
B)35.7 mm
C)8.93 mm
D)4.46 mm
E)25.2 mm

Question

Quizplus · Accepted Answer

For a 180° phase change, the thickness of the antireflective coating (d) should be equal to λ/4n, where λ is the wavelength of the radar waves and n is the refractive index of the polymer.

d = λ/4n = 6.00 cm / (4 x 1.68) = 0.0893 m = 8.93 mm

Therefore, the thickness of the antireflective coating should be 8.93 mm, which is option C).

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