1. The problem statement, all variables and given/known data The critical angle for a special glass in air is 44 degrees. What is the critical angle if the glass is immersed in water? 2. Relevant equations sin(critical angle) = 1/index of refraction index of refraction of air is 1.00 index of refraction of water is 1.333 3. The attempt at a solution I have no clue where to start that's the problem :S. Just for reference, the textbook answer is 68 degrees. Thanks.