A cell has an image length of 40 mm under a microscope magnification of ×500. What is its actual length in micrometres?
Answer and explanation
Correct answer: B. 80 μm
- Step 1: Actual size = image size ÷ magnification, with 40 mm = 40000 μm. Step 2. 40000 ÷ 500 = 80 μm. Answer: 80 μm. Why not the others: 2/25 μm is what you get if you forget to convert mm to μm. 20000 μm is what you get if you multiply by the magnification. 800 μm is what you get if you convert incorrectly.
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