In unit prefixes used across engineering and physics, the thickness called a 'micron' (micrometre) corresponds to which length in metres?
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A10^-3 m
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B10^-6 m
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C10^-9 m
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D10^-12 m
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E10^-2 m
Answer
Correct Answer: 10^-6 m
Explanation
Introduction / Context:Engineers often encounter micro-scale dimensions in materials science, manufacturing tolerances, filtration, and biology. The term 'micron' is a common, older name for the micrometre, a standard S.I. submultiple of the metre that simplifies expression of very small lengths.
Given Data / Assumptions:
- We must map 'micron' to a power-of-ten metre length.
- Common small-scale prefixes: milli (10^-3), micro (10^-6), nano (10^-9), pico (10^-12).
- Spelling note: micrometre (µm) is the S.I. term; micron is non-S.I. but widely used.
Concept / Approach:
Recall S.I. prefixes: micro (symbol µ) denotes 10^-6. Therefore, 1 micrometre = 1 µm = 10^-6 m. Many industrial specifications and scientific instruments reference µm for film thickness, surface roughness, and particle sizes.
Step-by-Step Solution:
Identify the relevant prefix: micro → 10^-6.Associate 'micron' with micrometre (µm).State equivalence: 1 µm = 10^-6 m → choose 10^-6 m.Verification / Alternative check:
Cross-check common conversions: 1000 µm = 1 mm, since 10^-6 m * 1000 = 10^-3 m. This aligns with milli (10^-3), verifying internal consistency.
Why Other Options Are Wrong:
- 10^-3 m: milli (mm), not micro.
- 10^-9 m: nano (nm).
- 10^-12 m: pico (pm).
- 10^-2 m: centi (cm) scale, far larger.
Common Pitfalls:
- Writing 'micron' but using mm or nm values in calculations.
- Confusing micro (µ) with milli (m) in unit symbols, which can cause 1000× errors.
Final Answer:
10^-6 m