What is Magnification Power?

Magnifying power is defined as the ratio between the dimensions of the image and the object.

The process of magnification can occur in lenses, telescopes, microscopes and even in slide projectors. Simple magnifying lenses are biconvex - these lenses are thicker at the center than at the edges.

The magnifying glass was one of the first ever instruments which was used to magnifying an object. Magnification relates to the scaling up of images in order to see the fine details by increasing the image resolution.

Types of Magnification and Calculation of Magnification Power

There are mainly two types of magnification - linear and angular:

• Linear or transverse magnification – This occurs for real images, like those projected on screens.
• Angular magnification – This type of magnification occurs in optical instruments that consist of an eyepiece. The size of the image is determined by the angle subtended by the object at the focal point.

The magnifying power of an instrument is the ratio between the angular size of the image as seen through the instrument and the angular size of the object as seen by the naked eye.

The calculation of the magnification power is based on three cases:

• Object and image at infinity
• Object at infinity but image at a finite distance
• Object at a finite distance

References and Further Reading 

• The Concept of Magnification – Florida State University
• Optical Microscopy – University of Arizona
• Telescope – Infoplease
• Properties of Optical Instruments – Paris tech