1. The problem statement, all variables and given/known data Parallel light rays enter a transparent sphere along a line passing through the center of the sphere. The rays come to a focus on the far surface of the sphere. What is the sphere's index of refraction? 2. Relevant equations 3. The attempt at a solution so I used the equation that relates object distances and image distances for spherical surfaces: n1/s + n2/s' = (n2-n1)/R I am calling the radius of the sphere R (1.00)/s + n2/2R = (n2-1.00)/R and I think for this case s[tex]\rightarrow[/tex][tex]\infty[/tex] so n2/2R = (n2-1)/R n2 = 2(n2-1) n2 = 2n2 -2 -n2=-2 so n2= 2.00 Is this correct?