hit Reset All Part 4. 1) Set your top (incident) medium as glass. Set your bottom (refracted) medium as air. Using the values for n, find at what angle light will be retracted in air if it is incident at an angle of 55 in glass. Show your work. What did you get for your angle of refraction? 2) Turn on the Laser and put it at 55. What happens? Does this explain what is going on with your solution to Snell's Law? 3) The greatest angle that a substance can retract is 90. 0) Move your slider around until you can get light to retract at 90. What was your incident angle? An angle that makes light retract at 90 degrees is called the critical angle of incidence. 9i critical: to make light refract at 90