Post on 07-Aug-2018
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CALCULATION OF LEAST
COUNT IN METRIC &
IMPERIAL SCALESBy: VerniersCaliper.com
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WHAT IS A LEAST COUNT?
A scale is the defining feature of any measuring
instrument. Usually measurements are taken by
placing an object on top of a scale and noting the
distance between the edges. In this case a larger
number of divisions on the scale leads to a moreaccurate measurement and vice versa.
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The technical term used to describe this parameter is
known as least count, which is the smallestmeasurement which can be measured by a scale. Its
value can be obtained by the division of one unit on the
scale by the number of divisions that lie in between.
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REMEMBER
The correct determination of the least count of a
vernier caliper is important for the measurement
to be accurate. This is a common difficulty faced
by people, even engineers and leads to incorrect
readings while measuring heights, diameter,lengths etc. Sometimes both metric and imperial
units together on the scale may also cause
confusion.
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ABOUT
This article will tell you the procedure for
calculating the least count of a vernier caliper.
The smallest measurement which can be
recorded by the Vernier caliper is defined as the
least count.
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DETERMINE THE
LEAST COUNT
First we need to determine the least count of the main
scale which can be done as described previously. Then
we need to count the number of divisions on the vernier
scale and divide the least count of the main scale by it.
This will give us the least count of the vernier caliper.
The formula for this can be expressed as:
Least Count of Vernier Caliper = Main Scale
least count/ number of Vernier scale divisions
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CALCULATION OF LEAST
COUNT OF VERNIER
CALIPERS IN METRIC SCALE
In metric scales, the units used for calibration are
millimeters i.e. one division equals 1 cm and is divided
into further divisions in millimeters. The least count
can be calculated by dividing 1 cm by the number ofdivisions that lie between a unit. This way a main
scale which contains 10 divisions in a centimeter will
have a least count of 1/10 = 0.1cm or 1 mm.
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Similarly the vernier scale is also normally divided into
ten equal parts. Count the divisions on the vernier
scale just to make sure. The least count of the vernier
caliper can now be found by dividing the least count ofthe main scale by the number of divisions on the
vernier scale.
Usually the least count of the main scale is 0.1 m andthe vernier scale has 10 divisions so the least count
would be0.1/10 = 0.01cm.
The least count is related to accuracy in such a way thatif a vernier caliper has a least count of 0.01cm then it
is said to also have an accuracy of 0.01 cm.
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if you want to calculate the least count in mm, here isthe formula below:
Vernier caliper least count in mm = Vernier caliper least
count incm x 10
So in this case it would be;0.001 x 10 = 0.01mm,
therefore0.01 mm is the least count in millimeters for
this Vernier caliper.
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CALCULATION OF
LEAST COUNT OF VERNIER CALIPERS IN
IMPERIAL SCALE
There are two types of imperial Vernier calipers
discussed in the examples:
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TYPE 2 IMPERIAL VERNIER
CALIPERS
If there are 25 divisions on the Vernier Scale
If the vernier scale is divided into 25 parts then the
smallest measurement possible from the main scale
would be 0.025 inches.
Therefore least count of the Vernier Caliper is
calculated by the same formula i.e. dividing 0.025
by 25 = 0.001 inch
We can say that 0.001 inch is the accuracy and least
count for type 2 of imperial Vernier Caliper.
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For Further Information
Related to the Topic of
Calculation of Least CountIn Vernier Caliper
http://vernierscaliper.com/vernier-caliper-calculation-of-least-count-in-metric-imperial-scales-213.htmlhttp://vernierscaliper.com/vernier-caliper-calculation-of-least-count-in-metric-imperial-scales-213.html