Question

suppose you a viewing a slide using the high power (40x) objective lens. which adjustment knob(s) can you safely use when this objective is in place? only the coarse adjustment knob only the fine adjustment knob both the coarse adjustment knob and the fine adjustment knob

Explanation:

When using the high - power (40x) objective lens on a microscope, the coarse adjustment knob moves the stage up and down by a relatively large amount and can easily damage the slide or the lens. The fine adjustment knob moves the stage in small increments and is safe to use to get a sharp focus.

Answer:

Only the fine adjustment knob