Which function does the smaller knob on a microscope serve?

The smaller knob on a microscope is typically used for fine adjustments. This finer adjustment knob enables precise focusing by allowing small movements of the stage or the objective lenses, which is crucial when viewing specimens at higher magnifications. When using high-power objectives, even the slightest adjustments can make a significant difference in clarity since the focal plane is much thinner. This knob is essential for achieving a sharp, focused image after using the coarse adjustment knob to bring the specimen into general focus.

In contrast, the larger knob is generally used for coarse adjustments, moving the stage or lenses more substantially, while other knobs or features may be dedicated to controlling light intensity or stage movement.