1. The problem statement, all variables and given/known data The drawing shows a crystalline quartz slab with a rectangular cross-section. A ray of light strikes the slab at an incident angle of 1=34o, enters the quartz and travels to point Po (Figure2). This slab is surrounded by a fluid with a refractive index n. What is the maximum value of n such that total internal reflection occurs at point Po? @1= 34deg n2= 1.544 2. Relevant equations n1sin@1 = n2sin@2 @c = sin-1 (n2/n1) 3. The attempt at a solution Well I know in order to find n1 I need to know the critical angle, but I don't know how to find the critical angle without n1. My only idea was to use Snell's law of refraction to find n1 by setting @1 at 90deg?