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Logic Behind Vernier Calliper

  1. Oct 6, 2014 #1
    I have made measurements using Vernier Calipers. What I don't understand about them is the coinciding thing. How does one know the value of the last digit of the measurement by seeing which marker of the main scale coincides with the Vernier scale?
     
  2. jcsd
  3. Oct 6, 2014 #2

    Nugatory

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    Google for "how a vernier caliper works". You'll get a bunch of hits that just tell you how to read one without explaining why it works, but mixed with them are a few that explain WHY it works. http://www.marinesite.info/2012/02/how-does-vernier-scale-work.ht [Broken] isn't the best one out there, but it's OK.
     
    Last edited by a moderator: May 7, 2017
  4. Oct 6, 2014 #3
    The link says the page you are looking for does not exist anymore.
     
  5. Oct 6, 2014 #4
  6. Oct 7, 2014 #5

    CWatters

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    Someone once explained it to me like this....

    A vernier has a correct scale and an "incorrect" scale where the spacing between the divisions is has a deliberate small error. If the vernier is set to zero you get a misalignment between the two scales at every mark. When the vernier is set with the scales deliberately misaligned (as when measuring something) the error cancels out after a certain number of divisions and the marks come back into alignment.

    Suppose you have a loan from the bank that is meant to be repaid at £100 a month. If you only repay it at $99 a month then each month you will be $1 out. If you put in an extra $7 at the outset than after 7 months you will have repaid the correct amount. If you put in $12 at the outset then after 12 months you will have repaid the correct amount etc.
     
  7. Oct 7, 2014 #6

    sophiecentaur

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    The vernier scale can be very confusing, both to read and to understand!
    Try the wiki entry here
     
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