Express the current 3.2 × 10^-5 amperes using an appropriate SI metric prefix (choose the best single-prefix notation).
Electronics
Quantities and Units
Difficulty: Easy
Choose an option
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A32 µA
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B3.3 µA
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C320 mA
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D3,200 mA
Answer
Correct Answer: 32 µA
Explanation
Introduction / Context:Working comfortably with powers of ten is essential when reading sensor outputs and specifying component ratings. We convert a scientific-notation current into a compact metric-prefix form.
Given Data / Assumptions:
- Given current: 3.2 × 10^-5 A.
- Prefixes: micro (µ) = 10^-6; milli (m) = 10^-3.
- Goal: a single, clear metric-prefix expression.
Concept / Approach:Express amperes in microamperes by dividing by 10^-6, or equivalently multiply the numeric coefficient by 10 (since 10^-5 A = 10 * 10^-6 A). This keeps the coefficient between 1 and 1000 with a single prefix.
Step-by-Step Solution:
Rewrite 3.2 × 10^-5 A as (3.2 × 10) × 10^-6 A.Compute the coefficient: 3.2 × 10 = 32.Use the µA prefix: 10^-6 A = 1 µA → result = 32 µA.Verification / Alternative check:Direct decimal move: 3.2 × 10^-5 A = 0.000032 A. Since 1 µA = 0.000001 A, divide 0.000032 / 0.000001 = 32 µA. Same result.
Why Other Options Are Wrong:
- 3.3 µA: Rounds and changes the value; not exact.
- 320 mA and 3,200 mA: Use milli (10^-3), producing values thousands to millions of times larger than given.
Common Pitfalls:
- Mistaking milli for micro due to similar symbols (m vs µ).
- Introducing rounding where exact conversion is requested.
Final Answer:32 µA