Final answer:
The ocular lens, or eyepiece, is part of a microscope that magnifies the image of a sample when used in combination with objective lenses. The ocular typically magnifies by 10x, and the total magnification is the product of the ocular and objective lens's magnifications. Microscopes use parfocal objective lenses for easier focusing and viewing of magnified images.
Step-by-step explanation:
The ocular lens, often referred to as the eyepiece, is a crucial component of optical instruments like microscopes and telescopes. In a microscope, the ocular lens works together with the objective lens to magnify the image of the sample being observed. The objective lens, mounted on a rotating nosepiece, typically offers magnifications ranging from 4x to 100x, and the ocular lens usually provides a magnification of 10x. Total magnification is calculated by multiplying the magnification of the ocular lens with that of the selected objective lens. Both the objective and ocular lenses are key to producing a clear and enlarged image that can be easily viewed, as the human eye is not capable of focusing on very close objects.
Microscopes, which originated in the early 1600s, have evolved to use multiple lenses and mirrors for more sophisticated imaging. When switching between different objective lenses, a feature known as parfocal allows the sample to stay in focus, simplifying the viewing process. The final image produced is large enough to be easily observed, thanks to the additional magnification provided by the ocular lens.