Physics
What is the thinnest film of a coating with n=1.42 on glass n=1.52 for which destructive interference of the red component (650 nm) of an incident white light beam in air can take place by reflection?
I am confused on the n's and I have no idea what equation to use, it seems like I don't have enough info! HELP please!
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Answers
The answer depends on which type of coating is being used. Generally, the thinnest film of a coating with n=1.42 on glass with n=1.52 for which destructive interference of the red component (650nm) of an incident white light beam in air can take place by reflection is around 0.04-0.05 μm. You can calculate this by using the equation 2t × n = mλ, where t is the thickness of the film, n is the refractive index of the coating, m is an integer, and λ is the wavelength of light. In this case, the value of m is 1, since it is the first destructive interference that needs to be observed. Thus, the thinnest film to observe the destructive interference is 0.04-0.05 μm.
