Magnification by microscopes unlocked a hidden world.
Telescopes, microscopes, binoculars and reading glasses make small objects appear larger and distant objects appear closer. This ability, termed magnification, relates the size, orientation and distance of the image to the object.
Linear Magnification
Linear magnification is the ratio of the image to the object using either size or distance (linear magnification = image height/object height = distance to image/distance to object). When calculating, assign a negative value to the image. The resulting magnification will then have a negative or positive value indicating a real or virtual image.
Real and Virtual Images
If the linear magnification is negative, the image is inverted and termed a real image. If the linear magnification is positive, the image is upright and called a virtual image. Microscopes are an example of virtual images with the image inverted compared to the specimen. Magnifying lenses exemplify virtual images with both the image and object oriented in the same direction.
Angular Magnification
Microscopes and telescopes produce a virtual image at infinite distance in the eyepiece. Instead of linear magnification, these instruments rely on angular magnification.
Magnification in Microscopes
The total magnification of a microscope is determined by the ocular lens magnification multiplied by the objective lens magnification (magnification = ocular lens x objective lens).
Magnification in Telescopes
Magnification in telescopes is calculated by dividing the focal length of the objective lens by the focal length of the eyepiece (magnification = telescope focal length/eyepiece focal length).
Tags: focal length, image object, linear magnification, objective lens, virtual image
