Final answer:
The fine adjustment knob should only be used with the 100x objective.
Step-by-step explanation:
The fine adjustment knob should only be used with the 100x objective.
The fine adjustment knob is used to bring the specimen into sharp focus when using high magnification objectives, such as the 100x objective.
Using the fine adjustment knob with lower magnification objectives, such as the 10x or 40x objectives, may result in damaging the microscope or the slide.
Learn more about fine adjustment knob and microscope objectives