explain o -12 points Ser PSE9 37 P032 O Asa Your Teache A material having an ind

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explain

o -12 points Ser PSE9 37 P032 O Asa Your Teache A material having an index af refraction of 1.3s is used as an antireflective coating on a piece of glass (n 1.50), what should be the minimum thickness of this film in order to minimize reflection of 470 nm light? Need Help? Read -/2 points SerPSE9 37 P D33 Mi FB y Notas Ask Your Teache A possible means for making an airplane invisible to radar is to coat the plane with an antireflective polymer ir radar waves have a wavelength of 3-08 cm and the index of refraction of the polymer is n 1.44e how thick wauld you make the coating? (Assume that the index of refraction of the plane is higher than that of the coating. Also assume that the radar waves are normal to the surface af the coating. Give the minimum thickness that would make the airplane invisible to Need Help? Read

Explanation / Answer

1)

  t = / 4n
= 470 / 4*1.35
= 87.037 nm

2)

n = 1.44

T = 3.08 cm/4n T = 3.08 cm/4x1.44 = 0.534cm

You need to have a thickness = 1/4 of a wavelength in the material. It will reflect off the back of the coating with a phase change and the wave on the top will also have reversed its phase. Therefore to be 1/2 wavelength out of phase to destructively interfere, the thickness of the path must = 1/2 wavelength and you need to divide by 2 because it travels to the back and reflect towards the surface.

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