To determine the accuracy class of an instrument or the accuracy of your own measurements, it is sometimes necessary to determine the absolute error. The absolute error is the number by which your measurement result differs from the true value.
It is necessary
- - device (scales, clock, ruler, voltmeter, ammeter, etc.);
- - a piece of paper;
- - a pen;
- - calculator.
Examine the device with which you will take measurements. If you are measuring with a balance, check to see if the arrow is at zero before experimenting. If you are measuring a time period, use a watch with a second hand or an electronic stopwatch. Use an electronic thermometer to measure temperature, not a mercury one. Select the device with the maximum number of divisions, the more divisions, the more accurate the result will be.
Take several measurements, the more results there are, the more accurately the true value will be calculated. For example, measure the length of the table several times or read the voltmeter several times. Make sure that all measurements were made accurately, and do not differ much in size, exclude gross errors.
If all results are the same, conclude that the absolute error is zero or that the measurement is too coarse.
If the results differ, find the arithmetic mean of all measurements: add all the results obtained and divide by the number of measurements. Thus, you are as close as possible to finding out the true value, for example, the length of the table or the voltage in the wires.
To find the absolute error, take one of the values, for example, the first measurement, and subtract it from the arithmetic mean calculated in the previous step.
Calculate the modulus of the absolute error, that is, if the number is negative, remove the "-" in front of it, since the absolute error can only be a positive number.
Calculate the absolute error of all other measurements.
Record the calculation results. The absolute error is denoted by the Greek letter Δ (delta) and is written as follows: Δх = 0.5 cm.