1. Are all convex lenses also converging lenses? The attempt at a solution Convex refers to shape. Converge refers to action. My answer is yes, provided that the material the lens is made of is denser than air, or denser than some other surrounding medium. Am i correct? OR are there other explanations? 2. What are the characteristics of a lens with a short focal length? The attempt at a solution We should divide the lens into 2 categories: namely converging and diverging. For a converging lens, the centre should be much fatter than at its edges. For a diverging lens, the centre should be much thinner than at its edges. Am i correct? 3. Suggest an application when an object is placed at the focal length of a lens I saw a textbook. It says that a real image is on opposite side of the object at infinity, in which case it is used in a spotlight. Another image which is virtual is on the same side of the object, also at infinity, in which case it is used in the eyepiece of a telescope. Can someone please explain how the real image (on the opposite side of the object) is formed please?? It really bugs me!