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Rev. Notes > AS > Measuring techniques
 
 
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Topics
 
Measurements Errors Random error
Systematic error Uncertainty Total uncertainity in addition / subtraction
Total uncertainty in multiplication and division Total uncertainty in power factor Total uncertainty in the average value of many measurements
Total uncertainty in the timing experiment Total uncertainty in the timing experiment Example 1 - Calculation of uncertainty
Least count Spring Balance Digital Balance
Protractor Micrometer Vernier calliper
Digital Ammeter Cathode Ray Osciloscope
 

Total uncertainty in the average value of many measurements

  1. Find the average value of measured values.
  2. Find deviation of each measured value from the average value.
  3. The mean deviation is the uncertainty in the average value.
  4. For example, the six reading of the micrometer screw gauge to measure the diameter of a wire in mm are

                  1.20,1.22,1.23,1.19,1.22,1.21.
Then          Average =  (1.20 + 1.22 + 1.23 + 1.19 + 1.22 + 1.21) / 6

Then         Average =  1.21 mm

The deviation of the readings , which are thedifference without regards to the sign, between each readings and average value are

0.01, 0.01, 0.02, 0.02, 0.01, 0

Mean deviations = (0.01 + 0.01 + 0.02 + 0.02 + 0.01 + 0) / 6

Mean deviation = 0.01 mm

Thus, likely uncertainty in the mean diameter 1.21 mm is 0.01 mm recorded as 1.21 ± 00.1 mm.

 
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View Comments on this Chapter - Total Comments (2)
 
unknown Said :
^to calculate the radius, diameter needs to be divided by 2. thus, 1.22/2 = 0.61
 
  02/01/15 12:33 AM
   
Bilal Said :
where did 0.6 come from in result
 
  09/09/14 02:51 PM
 

 

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