Images in Mirror and Lenses

General terms for forming images from lenses:

Images are:

• Real if they occur on the opposite side of the lens as the object. (R)
• Virtual if they occur on the same side of the lens to the object. (V)
• Upright if they are the same way up as the object. (U)
• Inverted if they are upside down. (I)
• Diminished if they are smaller than the object. (D)
• Magnified if they are larger than the object. (M)

General terms for forming images from mirrors:

Images are:

• Real if they occur on the same side of the lens as the object. (R)
• Virtual if they occur on the opposite side of the lens to the object. (V)
• Upright if they are the same way up as the object. (U)
• Inverted if they are upside down. (I)
• Diminished if they are smaller than the object. (D)
• Magnified if they are larger than the object. (M)

Note: Most terms are identical for lenses and mirrors except for real and virtual images.

Diagrams:

Drawing diagrams for lenses and mirrors is done to illustrate the magnitudes of various features. The features that are usually illustrated include:

= the distance between the object and the lens/mirror.

= the distance between the image and the lens/mirror.

= the height of the object.

= the height of the image.

= the focal length of the lens/mirror.

= the magnification of the image.

Equations:

The position and nature of the image formed by a lens is calculated using the lens formula:

The size of an image can be determined using the formula for magnification. Magnification is a ratio of the image to the object:

The following allows you to play around with a lenses and images.

Images formed by refraction in a convex lens:

Images formed by refraction in a concave lens:

Images formed by reflection in a concave mirror: