image

Definition: A representation of a physical object formed by a lens, mirror or other optical instrument. If the rays of light actually pass through the image, it is called a real image. If a screen is placed in the plane of a real image it will generally become visible. If the image is seen at a point from which the rays appear to come to the observer, but do not actually do so, the image is called a virtual image. No image will be formed on a screen placed at this point. Images may be upright or inverted and they may be magnified or diminished.