1. The problem statement, all variables and given/known data Light is incident along the normal to face AB of a glass prism of refractive index 1.47 Find the alpha max, the largest value of the angle alpha such that no light is refracted out of the prism at face AC if the prism is immersed in air. 2. Relevant equations n1*sin thetha1 = n2 * sin thetha2 3. The attempt at a solution since no light is refracted out of the prism, then total internal reflection is involved. sin critical alpha = (n2/n1)*sin 90 = 1.33/147 alpha = 64.8 but I got it wrong, please someone help me.. thanks..