Measurement Errors Practice Questions
20 free Measurement Errors practice questions for the General Science. Tap an option to answer — you get instant feedback, the correct answer, and a detailed explanation for every question.
Which type of error occurs when a measurement consistently deviates from the true value in the same direction?
- A Systematic error
- B Random error
- C Gross error
- D Percentage error
Correct answer: Systematic error
Systematic errors are reproducible inaccuracies that are consistently in the same direction. They often result from faulty equipment calibration or flawed experimental design.
An archer hits the bullseye consistently every time. In terms of measurement, this archer's performance is:
- A Accurate but not precise
- B Precise but not accurate
- C Both accurate and precise
- D Neither accurate nor precise
Correct answer: Both accurate and precise
Accuracy refers to how close a measurement is to the true value (the bullseye), while precision refers to how close repeated measurements are to each other. Consistently hitting the bullseye satisfies both criteria.
What is 'Parallax Error' in scientific measurements?
- A An error caused by the thermal expansion of the measuring scale when it is heated during use
- B A shift in an object's apparent position when viewed along two different lines of sight
- C An error caused by friction acting on the moving needle of an analog meter
- D A mistake made while transferring recorded data into a digital logbook
Correct answer: A shift in an object's apparent position when viewed along two different lines of sight
Parallax error occurs when the observer's eye is not directly aligned with the measurement scale. This is a common form of observational error when reading liquid levels in a graduated cylinder or needles on an analog meter.
Which of the following errors can be reduced by taking the average of a large number of repeated measurements?
- A Zero error
- B Random error
- C Instrumental error
- D Calibration error
Correct answer: Random error
Random errors are unpredictable and vary in both magnitude and direction. By averaging multiple readings, the positive and negative fluctuations tend to cancel each other out, leading to a more reliable mean value.
A weighing scale shows 0.5 kg even when there is no weight placed on it. This is an example of:
- A Random error
- B Zero error
- C Lag error
- D Environmental error
Correct answer: Zero error
Zero error is a type of systematic error where an instrument does not start at zero when the quantity to be measured is zero. It must be subtracted from or added to subsequent readings to get the correct value.
If a scientist uses a wooden ruler that has slightly shrunk over time, what kind of error will be introduced into all measurements?
- A Environmental error
- B Instrumental error
- C Random error
- D Calculation error
Correct answer: Instrumental error
Instrumental error arises from defects in the measuring instrument itself, such as poor construction or age-related degradation. In this case, the shrunk ruler will consistently underestimate the true length.
In measurement science, 'Precision' is defined as:
- A The closeness of a measurement to the true value
- B The smallest change in a measured quantity that an instrument can detect
- C The closeness of agreement between repeated independent test results
- D The total percentage of error in a calculation
Correct answer: The closeness of agreement between repeated independent test results
Precision describes the repeatability or reproducibility of measurements. An instrument can be highly precise (giving the same result repeatedly) even if it is not accurate (far from the true value).
Which formula is used to calculate the 'Percentage Error' of an experimental result?
- A $$(\text{Measured Value} - \text{True Value}) \times 100$$
- B $$\frac{\text{Measured Value}}{\text{True Value}} \times 100$$
- C $$\frac{|\text{Measured Value} - \text{True Value}|}{\text{True Value}} \times 100$$
- D $$\frac{\text{True Value} - \text{Measured Value}}{\text{Measured Value}} \times 100$$
Correct answer: $$\frac{|\text{Measured Value} - \text{True Value}|}{\text{True Value}} \times 100$$
Percentage error expresses the relative size of the error compared to the true value. Taking the absolute difference ensures the error is expressed as a positive percentage of the accepted value.
A digital stopwatch that runs 1 second slow every minute introduces which category of error?
- A Systematic error
- B Random error
- C Gross error
- D Environmental error
Correct answer: Systematic error
Because the clock consistently loses time at a predictable rate, it is a systematic error. This can usually be corrected if the rate of error is known (calibration).
The 'Least Count' of a measuring instrument refers to:
- A The maximum value the instrument is able to display on its scale
- B The smallest value the instrument can measure accurately
- C The error caused by the user's reaction time
- D The average value of ten consecutive readings
Correct answer: The smallest value the instrument can measure accurately
The least count is the smallest division on the scale of a measuring instrument. For example, the least count of a standard metric ruler is usually 1 mm.
When reading the volume of water in a glass graduated cylinder, the correct measurement should be taken from the:
- A Top of the meniscus
- B Bottom of the meniscus
- C Middle of the meniscus
- D Average of the top and bottom
Correct answer: Bottom of the meniscus
Water forms a concave meniscus in glass due to adhesion. Measuring from the bottom of the curve ensures consistency and matches the calibration of the glassware.
Which of the following is considered a 'Gross Error'?
- A Air resistance affecting a pendulum
- B Expansion of a metal tape measure
- C Random thermal noise in a sensitive electronic circuit
- D Misreading a scale or recording data incorrectly
Correct answer: Misreading a scale or recording data incorrectly
Gross errors are essentially 'blunders' caused by human oversight or carelessness. They are not inherent to the system or the instrument and can usually be avoided by careful work.
The concept of 'Significant Figures' is primarily used to represent the __________ of a measurement.
- A Accuracy
- B True Value
- C Systematic Error
- D Precision
Correct answer: Precision
Significant figures communicate the precision of the instrument used. They include all certain digits plus one final estimated digit.
Environmental errors are a sub-type of systematic errors. Which of these is an example of an environmental error?
- A A person with a slow reaction time when starting and stopping a stopwatch
- B A voltmeter being dropped and losing its calibration
- C Changes in humidity affecting the mass of a hygroscopic chemical
- D Mistyping a number into a calculator
Correct answer: Changes in humidity affecting the mass of a hygroscopic chemical
Environmental errors occur due to external conditions like temperature, pressure, or humidity. In this case, the moisture absorbed by the chemical changes its measured mass.
A 'Backlash Error' is most commonly found in which type of instrument?
- A Digital multimeter
- B Glass thermometer
- C Micrometer screw gauge
- D Liquid-filled barometer
Correct answer: Micrometer screw gauge
Backlash error occurs in screw-based instruments when the direction of rotation is reversed. It is caused by the gaps or 'play' between the gears or screw threads.
What happens to the relative error of a measurement as the magnitude of the quantity being measured increases?
- A It increases
- B It stays the same
- C It becomes zero
- D It decreases
Correct answer: It decreases
Relative error is the ratio of absolute error to the true value. For a constant absolute error (like the least count of a ruler), measuring a larger object results in a smaller relative (percentage) error.
An experimenter uses a pendulum to calculate gravity but forgets to account for air resistance. This is an example of:
- A Instrumental error
- B Random error
- C Gross error
- D Theoretical error
Correct answer: Theoretical error
Theoretical errors (or modelling errors) occur when the mathematical model or the simplifying assumptions used do not perfectly match reality. Ignoring air resistance is one such simplification.
In the context of the 'Standard Deviation' of a set of measurements, a low standard deviation indicates high:
- A Accuracy
- B Zero Error
- C Sensitivity
- D Precision
Correct answer: Precision
Standard deviation measures the spread of data. A low standard deviation means the measurements are close to the mean, which signifies high precision.
Which of these practices is the best way to identify a systematic error in an experiment?
- A Measuring the same quantity with a different calibrated instrument
- B Repeating the same experiment 100 times using exactly the same equipment
- C Hiring a more experienced person to take the readings
- D Rounding all the numbers to two decimal places
Correct answer: Measuring the same quantity with a different calibrated instrument
Systematic errors cannot be discovered by simple repetition. Comparing results with a different independent method or a 'standard' instrument is necessary to reveal consistent biases.
A Vernier Calliper is generally more precise than a standard ruler because it has a smaller:
- A Least count
- B Total length
- C Zero error
- D Parallax error
Correct answer: Least count
The Vernier scale allows for measurements down to fractions of a millimeter (often 0.02 mm or 0.1 mm), which is much smaller than the 1 mm least count of a standard ruler.