What is the best procedure for focusing a compound light microscope? a) use a visual inspection of the object to determine which objective lens to use first. b) begin to focus using the highest power objective lens in order to detect small objects. c) begin to focus using the highest power objective lens and switch to other lenses as necessary. d) begin by using the lowest power objective lens and then switching to the next highest power lens.

The correct answer will be option-D.

Explanation:

A microscope is an instrument used to see the microscopic objects by placing the samples on a transparent slide and observing it by focusing the beam of light and electrons.

Focusing the slide in a microscope begins with adjusting and focusing on the lowest power lens of the objective lens (closer to object). The available lens in objective piece is 4X, 10X, 40X and 100X.  So, start with a lower power lens that is 4X and then switches to a higher level to 10X, 40X and 100x.

Thus, Option-D is the correct answer.