1. The problem statement, all variables and given/known data A beam of parallel light rays from a laser is incident on a solid transparent sphere of index of refraction n1 (see figure). (a) If a point image is produced at the back of the sphere, what is the index of refraction of the sphere? (b)What index of refraction, if any, will produce a point image at the center of the sphere. 2. Relevant equations n1/p + n2/i = (n2-n1)/r 3. The attempt at a solution n1 ~ 1.0 for air i = 2r Assuming that the factor n1/p -> 0 since the object is so far away that the light rays are parallel (is this assumption correct?) (a) Substituting for n1 and i: n2/2r = n2/r - 1/r n2/2r - n2/r = -1/r n2 (1/2r - 2/2r) = -1/r n2(-1/2r) = -1/r n2 = 2 This is the correct answer, but I want to make sure my assumption above was correct and I didn't just luck out. (b) Using the same equation from part 2 above, but substituting i = r, n2/r = n2/r - 1/r 0 = - 1/r In order for this to be true, the sphere would have to be infinitely large so, realistically, there is no value of r that would place the image at the center of the sphere.