when you look through a simple light microscope or a magnifying glass, you are looking through a biconvex lens (one that’s bent like the back of a spoon on both sides) made of glass. the object being viewed is on the far side of the lens. light from the object passes through the lens and is bent (refracted) towards your eye, so it seems as though it comes from a much bigger object.
in practice, modern microscopes contain a series of lenses rather than just one. they have an objective lens (which sits close to the object) and an eyepiece lens (which sits closer to your eye). both of these contribute to the magnification of the object. the eyepiece lens usually magnifies 10x, and a typical objective lens magnifies 40x. (microscopes usually come with a set of objective lenses that can be interchanged to vary the magnification.) you can calculate the total magnifying power of the microscope by multiplying the magnifying powers of the objective lens and the eyepiece (so 10 x 40 = total magnification of 400x).
including more lenses doesn’t change the basic principle of how a microscope magnifies but it does enable higher magnifications and gives a better quality image.
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