A possible means for making an airplane invisible to radar is to coat the plane with an anti reflective polymer. If radar waves have a wavelength of 3.00 cm and the index of refraction of the polymer is `mu=1.5`. How thick is the oil film? Refractive index of the material of airplane wings is greater than the refractive index of polymer.

Explanation

`2mut = lambda//2`
This is the condition for destructive interference .
`:. t= lambda/(4mu) = (3.0)/ (4xx 1.5) = 0.5 cm`