When using a light microscope, you begin viewing a slide using the ___________ objective lens.

• A. oil immersion (100x)
• B. scanning (4x)
• C. high-power (40x)
• D. low-power (10x)

Answer: (B)

Verified step by step guidance

1. Understand the purpose of each objective lens on a light microscope: the scanning (4x) lens is used for initial viewing to locate the specimen, the low-power (10x) lens provides a closer look, the high-power (40x) lens offers more detail, and the oil immersion (100x) lens is used for the highest magnification with oil to improve resolution.
2. Recognize that when starting to view a slide, you want to use the lens that gives the widest field of view and the lowest magnification to easily find the area of interest on the slide.
3. Identify that the scanning objective lens, which is 4x magnification, provides the widest field of view and is designed for this initial step.
4. Recall that after locating the specimen with the scanning lens, you can switch to higher magnification lenses (10x, 40x, or 100x) to observe finer details.
5. Therefore, the correct objective lens to begin viewing a slide is the scanning (4x) objective lens.