Uncertainties and errors in measurement

Decide the number of significant figures: 409.10

• 3

• 4

• 5

• 6

Decide the number of significant figures: 4091.00

• 3

• 4

• 5

• 6

A measurement result is considered ________ if it is judged to be close to the true value. It is influenced by random and systematic errors.

• Precise

• Accurate

• An error

• Resolution

A quality denoting the closeness of agreement (consistency) between values obtained by repeated measurement. It is influenced by random effects and can be expressed numerically.

• Repeatability

• Precision

• Uncertainty

• Resolution

The smallest change in the quantity being measured that causes a perceptible change in the output of the measuring device. This is usually the smallest measuring interval.

• Resolution
• Repeatability
• Precision
• Error

Any measurement will have some ____________. This will come from variation in the data obtained and be subject to systematic or random effects. This can be estimated by considering the instruments and the method and will usually be expressed as a range such as 20 ± 2 °C.

• Error

• Precision

• Reproducibility

• Uncertainty

The dashed line in the image represents

• The error bars

• The uncertainty

• Line of best fit

• Line of worst fit

The first length measured in a laboratory experiment is 2.5 + 0.1 m and the second length 3.4 + 0.1 m. What is the uncertainty of the difference in the lengths?

• 0.1 m

• 0.2 m

• 0.3 m

• 0.4 m

The first length measured in a laboratory experiment is 2.5 + 0.1 m and the second length 3.4 + 0.1 m. What is the uncertainty of the sum of the lengths?

• 0.1 m

• 0.2 m

• 0.3 m

• 0.4 m

True or False?

Repeating a reading never removes the systematic error.

• True

• False