Question

Two convex lenses of same thickness are used to make two different materials - glass and diamond. Which lens will have greater focal length?

Answer 1

The focal length of an object depends on the bending of light rays by the object. The higher the bending of light, the lower will be the focal length. Comparing glass and diamond, the rate of bending of light rays is higher in diamond. Hence, diamond will have lesser focal length.
Glass has greater focal length.