When beginning your observations with a compound light microscope, you should use the ________ objective lens and the ________ adjustment knob.

• A. oil immersion objective; coarse adjustment
• B. low-power objective; coarse adjustment
• C. low-power objective; fine adjustment
• D. high-power objective; fine adjustment

Answer: (B)

Verified step by step guidance

1. Understand the purpose of the objective lenses on a compound light microscope: the low-power objective lens is used for initial scanning and locating the specimen because it provides a wider field of view and lower magnification.
2. Recognize the function of the adjustment knobs: the coarse adjustment knob is designed for making large changes in focus, which is helpful when you first begin observing a specimen to bring it roughly into focus.
3. Combine these concepts: when starting your observations, you should use the low-power objective lens to easily find the specimen and the coarse adjustment knob to quickly adjust the focus.
4. Remember that the fine adjustment knob is used for making small, precise focusing adjustments, typically after the specimen is already roughly focused with the coarse adjustment knob.
5. Note that the oil immersion objective lens is used for very high magnification and requires special handling, so it is not appropriate for beginning observations.