• Holding a magnifying glass against a wall at the proper distance usually will provide a picture of the lit-up parts of the room. Note that that distance varies, depending on the distance of the object concerned from the lens. Objects that are far away will require a distance called the focal length, while objects that are closer to the lens require a longer distance for a sharp picture of that object on the wall.
• Eye glasses restore proper sight to very many people, also eyepieces of optical instruments include lenses.
• Photography has many uses

See also wikipedia: List of many optics topics

Refraction at a spherical interface

See also wikipedia:Refraction

A lens

See also

• Physics Study Guide/Optics
• Waves/Geometrical Problems
• wikipedia: Lenses
• wikipedia:Optical devices