Question

Imagine that you have a very thin uniform oil film on the surface of water. The thickness of oil is much smaller than the wavelength of blue light. White light is shining on the film. What color would the film be if you looked at it from above? Explain.

Answer 1

Answer:

Green light

Explanation:

The thickness of oil is smaller than wavelength of blue light. The wavelength 450 nm to 495 nm. Let the thickness of oil is 400 nm.

By the constructive interference formula,

2nt = m$\lamda$$\lamda$λ

2 X 1.28 X 400 X 10^(-9) = 2λ

λ = 512 nm

This is the wavelength of green light.