A microscope is called a compound microscope because it uses two or more lenses to produce a magnified image of a specimen. The objective lens, which is located at the bottom of the microscope, gathers light from the specimen and focuses it on the image plane. The eyepiece lens, which is located at the top of the microscope, then magnifies the image produced by the objective lens.

The total magnification of a compound microscope is calculated by multiplying the magnification of the objective lens by the magnification of the eyepiece lens. For example, if a microscope has a 10x objective lens and a 10x eyepiece lens, the total magnification would be 100x.

Compound microscopes are used to view small specimens that cannot be seen with the naked eye. They are used in a variety of fields, including biology, chemistry, and medicine.