Magnification, scale bars & microscope measurement
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All 6 Flashcards — Magnification, scale bars & microscope measurement
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Question
What is the magnification formula?
Answer
$M = \dfrac{\text{image size}}{\text{actual size}}$ — both in the **same unit**. It's a ratio, so it has **no units** (write $\times N$).
Question
How do you calculate a real (actual) size?
Answer
Rearrange the triangle: $\text{actual} = \dfrac{\text{image size}}{M}$. Convert to one unit, then **divide the image size by the magnification**.
Question
How do you use a scale bar to find magnification?
Answer
Measure the bar on the image (e.g. $40\text{ mm} = 40\,000\ \mu\text{m}$), read the real distance it represents (e.g. $80\ \mu\text{m}$), then $M = 40\,000 \div 80 = \times 500$.
Question
How do you convert mm to µm (and why)?
Answer
**Multiply by 1000** ($1\text{ mm} = 1000\ \mu\text{m}$). Image lengths are in mm but cells are in µm — match units **before** dividing or you'll be 1000× out.
Question
If each division on an image is 2.5 µm and a cell spans 20 divisions, how long is it?
Answer
Real size = divisions × µm per division = $20 \times 2.5 = 50\ \mu\text{m}$.
Question
What equipment measures a cell's size down the microscope?
Answer
An **eyepiece graticule**, calibrated against a **stage micrometer** (not a plain ruler).
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Topic 5.1 hub
Experimental and data skills
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