If you use a compound light microscope, a 2-µm bacterial cell is best seen at which magnification?

• A. 400x
• B. 100x
• C. 40x
• D. 1000x

Answer: (D)

Verified step by step guidance

1. Understand the relationship between the size of the object and the resolving power of the microscope. A 2-µm bacterial cell is quite small, so you need sufficient magnification to see it clearly.
2. Recall that compound light microscopes typically have objective lenses with magnifications such as 4x, 10x, 40x, and 100x, combined with an ocular lens usually of 10x, resulting in total magnifications like 40x, 100x, 400x, and 1000x.
3. Calculate the total magnification by multiplying the objective lens magnification by the ocular lens magnification. For example, a 100x objective lens combined with a 10x ocular lens gives \(100 \times 10 = 1000x\) total magnification.
4. Consider the resolving power of the microscope, which is the ability to distinguish two points as separate. To clearly see a 2-µm bacterial cell, a higher magnification such as 1000x is generally required.
5. Compare the given options and recognize that 1000x magnification (usually achieved with a 100x objective and 10x ocular) is the best choice to observe a 2-µm bacterial cell clearly.