A scientist notices that an oil slick floating on water when viewed from above has many different rainbow colors reflecting off the surface. She aims a spectrometer at a particular spot and measures the wavelength to be 750 nm (in air). The index of refraction of water is 1.33. The index of refraction of the oil is 1.20. What is the minimum thickness t of the oil slick at that spot? _________________________________ I know that index of refraction = c/wavelength where c is a velocity.... Can anyone PLEASE give me a hint as to how I would approach this Question????