The overall enlargement achieved by a compound microscope is determined by multiplying the magnification power of the objective lens by the magnification power of the eyepiece lens. For example, if an objective lens has a magnification of 40x and the eyepiece has a magnification of 10x, the resulting image will appear 400 times larger than the original specimen. This resulting value reflects the extent to which the microscope increases the apparent size of the object being viewed.
Determining the final magnification is crucial in microscopy because it directly influences the level of detail that can be observed. A higher magnification allows for the visualization of finer structures and smaller objects that would otherwise be invisible. Historically, this understanding facilitated major advancements in fields like biology and medicine, allowing for the study of cells, microorganisms, and other microscopic entities. This capability continues to drive research and discovery across various scientific disciplines.