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Uncertainty conversions

  1. Mar 5, 2012 #1
    In a lab, i used a micro-caliper to measure the diameter of an indicator; I got [tex]3.681 mm \pm 0.005 mm[/tex]. However, i need the measurement to be in meters and i need to divide the measurement by 2 (as i need the radius, not diameter) for easy calculations. I know how to convert the 3.681 mm to meters, but what about the uncertainty?

    radius of indicator:
    [tex]3.681 mm * \frac{1 m}{1000 mm} * \frac{1}{2} = 0.00184\underline{0}5 m[/tex]

    [tex]\pm 0.005 mm * \frac{1 m}{1000 mm} * \frac{1}{2} = 0.00000\underline{2}5 m[/tex]

    Is this right?

    Thanks in advance.
    Last edited: Mar 5, 2012
  2. jcsd
  3. Mar 6, 2012 #2


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    Science Advisor

    Yes. It is easier to understand if you think of the uncertainty in terms of percentage uncertainty. Then the units don't matter.
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