Physical World & Units - Errors & Measurements

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Q1. What is the percentage error if the measured value is 10.0 and the true value is 9.5? (2021)

Solution:

Percentage error = (|Measured - True| / True) × 100 = (|10.0 - 9.5| / 9.5) × 100 = 5.26%.

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Q2. What is the percentage error if the measured value is 20.0 and the true value is 19.5? (2021)

Solution:

Percentage error = (|Measured - True| / True) × 100 = (|20.0 - 19.5| / 19.5) × 100 ≈ 2.56%.

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Q3. Which of the following is NOT a derived unit? (2023)

Solution:

Kilogram is a fundamental unit, while Newton, Joule, and Pascal are derived units.

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Q4. Which instrument is used to measure atmospheric pressure? (2020)

Solution:

A barometer is used to measure atmospheric pressure.

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Q5. In the context of measurements, what does precision refer to? (2022)

Solution:

Precision refers to the consistency of repeated measurements, regardless of their accuracy.

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Q6. Which of the following represents the concept of significant figures? (2023)

Solution:

Significant figures include all non-zero digits and any zeros between them or trailing after a decimal point.

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Q7. If a measurement is accurate, it means: (2019)

Solution:

Accuracy refers to how close a measured value is to the true value.

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Q8. What is the error in a measurement of 20.0 cm if the true value is 19.5 cm? (2023)

Solution:

The error is the absolute difference between the measured value and the true value, which is |20.0 - 19.5| = 0.5 cm.

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Q9. In a measurement, if the systematic error is known, how can it be corrected? (2020)

Solution:

Systematic errors can be corrected by subtracting the known error from the measured value.

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Q10. If a measurement is accurate but not precise, what does it imply? (2019)

Solution:

Accuracy refers to how close a measurement is to the true value.