O Level converging-lens ray diagrams: the three principal rays and the image characteristics for common object positions.

In this diagram, five incident rays are drawn along with their corresponding refracted rays. Each ray intersects at the image location and then travels to the eye of an observer. Every observer would observe the same image location and every light ray would follow the Snell's Law of refraction.

Converging lenses are used to focus light and form images. This module explores how thin lenses work, how to predict image properties using ray diagrams, and how they are used in everyday devices like cameras and projectors.

For an object inside the focal point, a virtual erect image will be formed. The ray diagrams for concave lenses inside and outside the focal point give similar results: an erect virtual image smaller than the object. The image is always formed inside the focal length of the lens.