A student is calibrating a light microscope using a stage micrometer and an eyepiece graticule. Under the ×40 \times 40\,×40 objective lens, each eyepiece division (eyepiece unit, epu\text{epu}epu) is equivalent to 2.5 μm2.5\ \mu\text{m}2.5 μm. Under this high-power lens, a plant cell vacuole measures 3.2 epu3.2\text{ epu}3.2 epu in width.
The student then switches to the low-power ×10 \times 10\,×10 objective lens. What is the width of this vacuole in eyepiece units (epu\text{epu}epu) under the ×10 \times 10\,×10 objective lens, and what is its actual width?
Width under ×10=12.8 epu\times 10 = 12.8\text{ epu}×10=12.8 epu; Actual width =8.0 μm= 8.0\ \mu\text{m}=8.0 μm
Width under ×10=0.8 epu\times 10 = 0.8\text{ epu}×10=0.8 epu; Actual width =8.0 μm= 8.0\ \mu\text{m}=8.0 μm
Width under ×10=0.8 epu\times 10 = 0.8\text{ epu}×10=0.8 epu; Actual width =1.28 μm= 1.28\ \mu\text{m}=1.28 μm
Width under ×10=3.2 epu\times 10 = 3.2\text{ epu}×10=3.2 epu; Actual width =8.0 μm= 8.0\ \mu\text{m}=8.0 μm
