Difficulty: Easy
Correct Answer: 5%
Explanation:
Introduction / Context:
Guaranteed accuracy is often specified as a percentage of full-scale (FS). When the reading is far below full-scale, the same absolute error corresponds to a larger percentage of the reading. Understanding this distinction is crucial for correct error reporting and for deciding appropriate instrument ranges.
Given Data / Assumptions:
Concept / Approach:
Absolute error at any reading = (accuracy% of FS) * FS. Limiting error as a percentage of the measured value = (absolute error / reading) * 100%. This converts a full-scale-based tolerance to a reading-based percentage, which is commonly requested in test reports.
Step-by-Step Solution:
Verification / Alternative check:
If the meter read 25 A, the same ±0.25 A would be ±1% of reading, matching the specification. Lower readings inflate the percent-of-reading error, which is a key reason to select the smallest meter range that safely covers the expected value.
Why Other Options Are Wrong:
Common Pitfalls:
Final Answer:
5%
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