1. The problem statement, all variables and given/known data Localize the image of an object situated at 1.2 m from a crystal ball with a diameter of 0.2 m (n=1.5). 2. Relevant equations None given. But Snell's law I believe. 3. The attempt at a solution I'm totally stuck at starting. Does the size of the object matters? Should I assume it as 1 or 2 dimensional? As a point? Or it doesn't matter? The image should be on the other side from the ball, right? I mean the image is real and not inside the ball, right? Thanks for getting me started.