Multiple Choice
Which part of a compound light microscope is primarily responsible for focusing the image by moving the stage up and down?
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5. Cell Components
Microscopes
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How do the coarse and fine focus knobs function on a brightfield microscope?
A
Both knobs are used only to adjust the intensity of the light source.
B
The fine focus knob moves the stage rapidly, and the coarse focus knob makes small adjustments for detail.
C
The coarse focus knob moves the stage rapidly to bring the specimen into general focus, while the fine focus knob makes small adjustments for sharp, detailed focus.
D
The coarse focus knob adjusts the objective lens magnification, and the fine focus knob changes the eyepiece magnification.
Verified step by step guidance1
Understand the purpose of the coarse and fine focus knobs on a brightfield microscope. These knobs are used to adjust the focus of the specimen being observed, not the intensity of the light source or magnification.
Recognize the function of the coarse focus knob. It moves the stage rapidly up or down to bring the specimen into general focus. This is typically used when initially locating the specimen under low magnification.
Identify the role of the fine focus knob. It makes small, precise adjustments to the stage position to achieve sharp and detailed focus on the specimen. This is especially useful under higher magnifications.
Clarify that neither the coarse nor fine focus knobs adjust magnification. Magnification is controlled by the objective lenses and eyepiece, not the focus knobs.
Summarize the correct answer: The coarse focus knob moves the stage rapidly to bring the specimen into general focus, while the fine focus knob makes small adjustments for sharp, detailed focus.
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