The Index of Refraction formula is: n = c / v, where c is the speed of light in vacuum and v is the speed of light in that substance. For water: n (water) = 1.33 1.33 = c / v(water) v(water) = c/1.33 For a certain substance: n = c : (0.83 * c/1.33) = 1.33 / 0.83 n = 1.6 Answer: The Index of Refraction of this substance is 1.6.
