What is linear magnification??

Magnification is the process of enlarging something only in appearance, not in physical size. Magnification is also a number describing by which factor an object was magnified. When this number is less than one it refers to a reduction in size, sometimes called minification.

Linear or transverse magnification — For real images, such as images projected on a screen, size means a linear dimension (measured, for example, in millimeters or inches).