A physical quantity is measured as 12.345 ± 0.005 units. The relative error in this measurement is approximately: MCQ with Answer and Explanation

A physical quantity is measured as 12.345 ± 0.005 units. The relative error in this measurement is approximately:
A. 0.04%
B. 4%
C. 0.4%
D. 0.004%
Answer: Option A
Solution (By JKExamLibrary)
Relative error = (Absolute error) / (Measured value) = 0.005 / 12.345 ≈ 0.000405. Converting to percentage: 0.000405 × 100% ≈ 0.0405% ≈ 0.04%. Relative error quantifies precision independent of measurement scale. Absolute error (±0.005) indicates instrument precision. This concept is vital for comparing measurement reliability across different magnitudes. Memory tip: Percentage error = (Absolute error / True value) × 100. Competitive exams often test this calculation with varying significant figures to assess numerical proficiency.

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