Question

A world has a dense atmosphere with index of refraction 2.00. There is a thin layer with index of refraction 1.33 that floats on the water and it has non-water oceans index of refraction of 1.17, what is the thinnest layer that would produce constructive interference of reflected 527 nm light incident from the sky?

Answer 1

Answer:- Condition for thin film constructive interfernce,    2 t cos r = (2n-1)/2

for minimum thickness, n=1

2 t_min= /2

t_min=

for thin film of refractive index, let ₂=1.33

₁=2

₁₂=2 /1=1.33/2=0.67    (this is the refractive index of thin film with respect to densed air.)

Hence in this world thin film also floats in non water ocean, because _ocean>_{thin film with respect to densed air}

so, t_min=527x10^-9/(4x0.67)

t_min=196.641x10^-9

t_min 2x10^-7 m=0.2 m