Notes On Uncertainty In Measurement - CBSE Class 11 Chemistry
In scientific notation, any number can be represented as N*10n, where n is an exponent having positive or negative values, and N is a coefficient that can vary between 1-10. If the average value of measurements is close to the correct value, the measurement is said to be accurate.





 Values of measurement close to each other          →




Average value is not close to the corresct value   →
      Person B
          100
          101
          102
          103
          104
          102



If the values of measurement are close to each other and close to their average value thus, the measurement is said to be precise. It is important to indicate the level of certainty and uncertainty in any measurement as it will affect the output or result of the experiment.

The certainty and uncertainty in a measurement is indicated through the use of significant figures. Significant figure is the total number of digits in a number, including the last digit whose value is uncertain.

Ex:
 Number  Number of Significant Figures
   897  Three
   0.23   Two
   9.87   Three
 Number  Number of Significant Figures
  0.0325   Three

If the last digit is greater than 5, then proceeding number is increased by one.
Ex: 7.46  It can be written as 7.5

Dimensional analysis is used to convert a given quantity from one type of unit to another unit.

Summary

In scientific notation, any number can be represented as N*10n, where n is an exponent having positive or negative values, and N is a coefficient that can vary between 1-10. If the average value of measurements is close to the correct value, the measurement is said to be accurate.





 Values of measurement close to each other          →




Average value is not close to the corresct value   →
      Person B
          100
          101
          102
          103
          104
          102



If the values of measurement are close to each other and close to their average value thus, the measurement is said to be precise. It is important to indicate the level of certainty and uncertainty in any measurement as it will affect the output or result of the experiment.

The certainty and uncertainty in a measurement is indicated through the use of significant figures. Significant figure is the total number of digits in a number, including the last digit whose value is uncertain.

Ex:
 Number  Number of Significant Figures
   897  Three
   0.23   Two
   9.87   Three
 Number  Number of Significant Figures
  0.0325   Three

If the last digit is greater than 5, then proceeding number is increased by one.
Ex: 7.46  It can be written as 7.5

Dimensional analysis is used to convert a given quantity from one type of unit to another unit.

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