Question

If the oil thickness is 200 nm and the index is 1.5, what (vacuum) wavelength (in nm) does a diver see looking at the same position as the scientist, but from under water?

Answer 1

Answer: 133.33nm

Explanation: refractive index, n = real depth/apparent depth

Oil thickness= real depth = 200nm

Wavelength from under the water = apparent depth = a

n = real depth/a

1.5 = 200/ a

a = 200/ 1.5

a = 133.33nm