Which part of the microscope should NOT be used when the high-powered objective lens is in place?

• A. Coarse adjustment knob
• B. Fine adjustment knob
• C. Stage clips
• D. Light source

Answer: (A)

Verified step by step guidance

1. Understand the function of each part of the microscope: The coarse adjustment knob is used for large movements to focus the image, the fine adjustment knob is for small, precise focusing, the stage clips hold the slide in place, and the light source illuminates the specimen.
2. Recall that the high-powered objective lens is very close to the slide and requires precise focusing to avoid damaging the slide or lens.
3. Recognize that the coarse adjustment knob moves the stage or lens significantly, which could cause the high-powered objective lens to collide with the slide.
4. Conclude that the coarse adjustment knob should NOT be used when the high-powered objective lens is in place, as it poses a risk of damage.
5. Instead, use the fine adjustment knob for precise focusing when the high-powered objective lens is in use.