What part of the light microscope adjusts the amount of light passing through?

The diaphragm is a crucial component of a light microscope that controls the amount of light entering the specimen. By adjusting the diaphragm, a user can increase or decrease the light intensity, which is essential for obtaining clear and well-defined images. Proper illumination is vital in microscopy because too much light can wash out details, while too little light can obscure visualization.

The objective lens, on the other hand, is responsible for magnifying the image of the specimen but does not control light intensity. Likewise, the stage is the platform that holds the slides but does not influence how much light passes through. The ocular lens, also known as the eyepiece, magnifies the image further for the viewer's eyes without adjusting the light levels. Therefore, the diaphragm stands out as the specific structure designed for light regulation in a light microscope.