Question 7 10 pts Calculate the minimum thickness (in nm) of an oil slick on water that appears blue when illuminated by white light perpendicular to its surface. Take the blue wavelength to be 469 nm and the index of refraction of oil to be 1.43. Your answer should be a number with one decimal place, do not include unit. 1 nm = 10-⁹m 11 air = 1 n n21.33 Water