Question

- A thin film of oil * (n = 1.45) on a puddle of water, producing different colors. What is the minimum thickness of a place where the oil creates constructive interference for light with a wavelength equal to 545 nm?

Answer 1

There will be a phase change at the first interface and no phase change at the second interface:

If the film is 1/4 wavelength thick this restriction will hold

The wavelength of the light in oil is 545 nm / 1.45 = 376 nm

376 nm / 4 = 94 nm

"D" is correct