I have one question about optics because I start interested in it. If an object is placed a distance p from a thin glass lens (index of refraction n), we can see its image on a screen that is placed a distance d from the lens. Do you know any formula which can describe this situacion? I found it in Czech internet, but I did not find some good. However, the most important is this part. Light does not spread in the liquid as well as in the air. So if I take this system to liquid, something will change. We have different conditions... The distance d isn't same if we want see image on a screen... Will be larger or smaller? And why? How can I calculate it? Do you know any internet page on this topic, or video with the attempt? Thanks very much and sorry for my English.