SQA National 5 Physics Practice Exam

A thicker lens has a shorter focal length compared to a thinner lens due to its greater curvature. The focal length of a lens is determined by its shape and the refractive index of the material from which it is made.

When light passes through a lens, it refracts or bends due to the change in speed as it enters and exits the different mediums. A thicker lens generally means that there is a greater difference in curvature between the two sides of the lens. This increased curvature enhances its ability to converge (or diverge) light rays more sharply, resulting in a shorter focal point—meaning that light rays parallel to the principal axis converge at a closer point to the lens compared to a thinner lens.

Thus, the characteristic feature of a thicker lens compared to a thinner lens is its ability to have a shorter focal length, making it capable of focusing light more sharply in applications like cameras or corrective eyewear.