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II.2. Determining the value of a physical parameter.

II.2.1. Direct measurement of length.

II.2.1.1. The dimensions of a body in space.

II.2.1.2. Measurement error.

Sources of error can be:

  • lack of accuracy of the measurement instrument;
  • incorrect reading of the instrument indications;
  • the lack of attention or skill of the person making the measurements;
  • unfavorable environmental conditions (inadequate lighting, too hot or too cold, discomfort, etc.).

If we perform length measurements with a ruler, the measurement accuracy cannot exceed the smallest gradation of the ruler - respectively 1 mm.

So the measurement error due to the instrument used is equal to the smallest division of the instrument.


At the micrometer the measurement error decreases to 1 micron, ie one millionth of a meter (1 / 1000000).

The existence of measurement errors in the case of experimental determinations is normal and in order to obtain a result as close as possible to the true value of the measured quantity, the measurements are repeated several times and the experimental data are processed as I will show you in the next experiment.

II.2.1.3. Apply what you have learned about Direct Length Measurement.

II.2.2. Direct area measurement.

II.2.3. Indirect determination of the area.

II.2.3.1 Apply what you have learned about Indirect Area Determination.

II.2.4. Direct measurement of the volume.

II.2.5. Indirect measurement of the volume.

II.2.5.1 Apply what you have learned about indirect measurement of the volume.

II.2.6. Direct measurement of the time interval.

II.2.6.1 Apply what you have learned about the direct measurement of the time interval.