physics :

Question 3 10 pts Calculate the index of refraction for a medium in which the speed of light is 2.146x108 m/s. The speed of light in vacuum is 3x108 m/s. Your answer should be a number with three decimal places, do not include the unit. E Question 4 10 pts You can determine the index of refraction of a substance by determining its critical angle. (a) What is the index of refraction of a substance that has a critical angle of (5.20 when submerged in water (nwater = 1.333)? Your answer should be a number with three decimal places, do not include the unit