Questions on Measurement Uncertainty
Multiple-Choice Questions – Measurement Uncertainty
1. What does measurement uncertainty refer to?
A) The exact value of a measurement
B) The range within which the true value is expected to lie
C) The average of multiple measurements
D) The error caused by using an incorrect instrument
E) The volume of an object
2. Which of the following causes measurement uncertainty?
A) Instrument precision limits
B) Operator skill
C) Environmental factors
D) All of the above
E) None of the above
3. How is measurement uncertainty usually expressed?
A) As an absolute value plus or minus a range
B) As a percentage without units
C) As a single number without units
D) As a probability distribution only
E) As a decimal number only
4. What is the difference between accuracy and uncertainty?
A) Accuracy refers to closeness to true value, uncertainty refers to doubt in measurement
B) Accuracy is the average, uncertainty is the highest value
C) Both mean the same thing
D) Accuracy refers to errors, uncertainty to precision only
E) Uncertainty is always larger than accuracy
5. Which instrument would generally have lower uncertainty?
A) A ruler marked to the nearest cm
B) A caliper marked to the nearest 0.01 mm
C) A bathroom scale with no decimal
D) A clock with only hour markings
E) A thermometer marked only at 5-degree intervals
6. How can measurement uncertainty be reduced?
A) Using instruments with higher precision
B) Taking multiple measurements and averaging
C) Improving technique and calibration
D) All of the above
E) Ignoring small variations
7. What does ± 0.02 cm represent in a measurement?
A) The exact measurement
B) The uncertainty range of the measurement
C) The average of two measurements
D) The precision of the instrument only
E) The error of the instrument
8. Why is measurement uncertainty important in scientific experiments?
A) It helps assess reliability of results
B) It ensures the measurement is perfect
C) It replaces the need for multiple trials
D) It increases the speed of measurement
E) It indicates the color of the sample
9. What is the uncertainty in a digital scale that reads to 0.01 g?
A) ± 0.1 g
B) ± 0.01 g
C) ± 1 g
D) ± 0.001 g
E) ± 0.5 g
10. When reporting a measurement with uncertainty, what should be included?
A) Only the value
B) The value and the uncertainty
C) The uncertainty only
D) The instrument brand
E) The number of trials
11. If a length is recorded as 12.34 cm ± 0.05 cm, what does 0.05 cm represent?
A) Accuracy
B) Uncertainty or error margin
C) The average length
D) The maximum length
E) The precision limit
12. How does taking multiple measurements affect uncertainty?
A) Increases uncertainty
B) Has no effect
C) Decreases uncertainty when averaged
D) Always eliminates uncertainty
E) Increases systematic error
13. What does a high uncertainty indicate about a measurement?
A) The measurement is very precise
B) The measurement is less reliable
C) The measurement is very accurate
D) The measurement is exact
E) The measurement is in error
14. Which of these is NOT a common source of uncertainty?
A) Instrument resolution
B) Human reaction time
C) Atmospheric pressure fluctuations
D) Standard reference value
E) Environmental vibrations
15. Which unit of measurement is most likely to have the smallest uncertainty?
A) Centimeter (cm)
B) Millimeter (mm)
C) Kilometer (km)
D) Meter (m)
E) Micrometer (µm)
16. What is the relationship between precision and uncertainty?
A) Higher precision means lower uncertainty
B) Higher precision means higher uncertainty
C) Precision and uncertainty are unrelated
D) Precision always equals uncertainty
E) Precision is half of uncertainty
17. What type of uncertainty arises from unpredictable fluctuations?
A) Systematic uncertainty
B) Random uncertainty
C) Instrumental uncertainty
D) Calibration uncertainty
E) Operator uncertainty
18. What method is commonly used to estimate uncertainty in repeated measurements?
A) Calculating the mean
B) Finding the range (max - min)
C) Calculating the standard deviation
D) Using the median only
E) Ignoring outliers
19. If you measure a mass as 50.0 g ± 0.1 g, what does this imply?
A) The mass is exactly 50.0 g
B) The mass is between 49.9 g and 50.1 g
C) The scale is faulty
D) The uncertainty is negligible
E) The mass is less than 50 g
20. Why is uncertainty typically included with measurements?
A) To quantify confidence in the measurement
B) To make the data look more complex
C) To confuse readers
D) To round numbers
E) To correct the measurement
Answer Key with Explanations
1. B) The range within which the true value is expected to lie
Uncertainty quantifies the doubt in a measurement.
2. D) All of the above
All these factors contribute to uncertainty.
3. A) As an absolute value plus or minus a range
Typically reported as measurement ± uncertainty.
4. A) Accuracy refers to closeness to true value, uncertainty refers to doubt in measurement
They measure related but different concepts.
5. B) A caliper marked to the nearest 0.01 mm
Higher precision means lower uncertainty.
6. D) All of the above
All these reduce uncertainty.
7. B) The uncertainty range of the measurement
Indicates possible error margin.
8. A) It helps assess reliability of results
Uncertainty quantifies confidence.
9. B) ± 0.01 g
Resolution dictates uncertainty.
10. B) The value and the uncertainty
Both are required for meaningful reporting.
11. B) Uncertainty or error margin
This shows the confidence range.
12. C) Decreases uncertainty when averaged
Averages reduce random error effects.
13. B) The measurement is less reliable
Higher uncertainty means less confidence.
14. D) Standard reference value
Reference values do not cause uncertainty.
15. E) Micrometer (µm)
Smallest unit listed has smallest uncertainty.
16. A) Higher precision means lower uncertainty
Precision relates to reproducibility, reducing uncertainty.
17. B) Random uncertainty
Due to unpredictable variations.
18. C) Calculating the standard deviation
Standard deviation is a measure of spread.
19. B) The mass is between 49.9 g and 50.1 g
Uncertainty defines this interval.
20. A) To quantify confidence in the measurement
Uncertainty expresses measurement reliability.
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