A thin film of oil with a thickness of 90 nm rests on top of a pool of water. When white light incident on the film is reflected, what color (wavelength of the first order) is seen? The refractive index of the oil is noil =1.45 and of water is nwater=1.33

m=0,  λ₀  = 522 10⁻⁹ m

Explanation:

In this case we can see that the first boy M The reflected light suffers an interference phenomenon, let's analyze what happens on each surface

* When light passes from a medium with a lower refractive index to a medium with a higher refractive index, it undergoes a phase change of pi rad (180º).

  This occurs when passing from air to oil, but not at the oil-water interface.

* within the material the wavelength changes by the refractive index

        λₙ = λ₀ / n

therefore introducing this into the constructive interference equation and assuming almost perpendicular incidence remains

         2 t = (m + ½) λₙ

         2t = (m + ½) λ₀ / n

        λ₀ = 2t n / (m + ½)

light in the first order (m = 1)

       λ₀  = 2 90 10⁻⁹ 1.45 / (1+ ½)

       λ₀  = 174 10⁻⁹ m

the light for zero order (m = 0)

         λ₀ = 2 90 10⁻⁹ 1.45 / (0+ ½)

         λ₀  = 522 10⁻⁹ m

this radiation in the visible range in the green region

answer: the metamorphic rocks are formed when they are exposed to high pressure and high temperatures. this happens when one of the earth's plates comes in contact with the other plate by traveling in opposite directions, straight into each other or slipping under one another. the friction that is caused by this activity results in   melting of rocks and when it cools they are known as metamorphic rocks. this process needs a controlled amount of pressure and temperature otherwise it may turn into magma.