BlogIIT-JEELeast Count and Significant Figures

Least Count and Significant Figures

A number’s significant figures are the digits that have meaning and contribute to its precision. As a result, the number of significant digits is determined by the measurement instrument’s least count. The significant figures in the measured value are all the certain digits plus one uncertain digit.

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    A Brief Outline

    Precision and accuracy are critical in science measurements. Scientists use large figures to demonstrate how exact their observations are. For within reason, we can consider these readings to be reliable.

    Important Concepts

    Every measurement is preceded by a degree of uncertainty. The measuring device and the skill of the individual doing the measuring are both sources of uncertainty. To represent this uncertainty, scientists report measurements with significant figures.

    As an example, consider volume measurement. Assume you’re in a chemistry lab and require 7 millilitres of water. You could use an unmarked coffee cup and fill it with water till it’s around 7 millilitres. In this scenario, the majority of the measurement error can be attributed to the measuring person’s expertise. You might use a beaker with 5 mL increments marked on it.

    You could easily get a volume of 5 to 10 mL with the beaker, perhaps close to 7 mL, give or take 1 mL. You could even get a volume between 6.99 and 7.01 mL with a pipette marked with 0.1 mL very consistently if you were using a pipette marked with 0.1 mL. Because you didn’t find the volume to the closest microliter, reporting that you measured 7.000 mL with any of this equipment would be false.

    Rules for Significant Figures

    The presence of non-zero digits is always meaningful.

    Between other significant digits, all zeros are significant.

    The least significant figure is the rightmost non-zero number if there is no decimal point. The least important figure in the number 5800 is ‘8.’

    Significance of least count and significant figures in IIT JEE exam

    Most of the problems are designed to assess conceptual knowledge. In terms of numbers, there were 13 problems from the class 11th curriculum and 17 questions from the class 12th syllabus. There were ten moderate, four easy, and two challenging questions concerning instrumentation systems in this section.


    Why are zeros at the end of a number not taken into account?

    The equivalent exponents of '10' in normal scientific notation could be used to replace the zeros just at the end of a whole number. As a result, they shouldn't be taken seriously.

    Is it necessary to write the answers in decimal or scientific notation?

    The responses can be written in decimal or scientific notation. Scientific notations are easier to read and can be used to represent exceedingly large or small amounts.

    Q. What are the 3 most significant guidelines for major figures?

    Ans: The 3 most significant rules of noteworthy figures are as follows:

    • Figures that are not zero can always be meaningful.
    • Even if there are zeros between two significant digits, they are still significant.
    • A trailing or final zero is crucial.
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