Vernier Calipers is a measuring device used to measure small length up to two decimal places.
It has two scales:
i)
Main scale
like ruler (in cm). This gives measure of length in one decimal place.
ii)
ii) Vernier
scale'(having ten division). This gives value of second decimal place.
Diagram:
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| Vernier Callipers |
Least count: It is the least distance which can be measured accurately by it is also called Vernier constant.
If 10 div of main scale = 9 div of Vernier scale
then
Least count of Vernier Callipers will be 0.01 cm
Zero error: If zero of Vernier scale not coinciding with zero of main scale, said to have zero error.
Types of errors:
1. Positive zero error- When zero of Vernier scale
right side of zero of main scale.
2 Negative zero error- When zero of Vernier scale left side of zero of main scale.
Zero error = + n x L.C,
where n is the division of Vernier coinciding with the any main scale division.
Calculation:
Length = M.S.R + V.S.D X L.C
True Length= Length- zero error with proper sign
(Where M.S.R - main scale reading,
V.S.D- Vernier scale division coinciding with main scale and L.C - least count)
Learn to measure:
Question: The least count of a vernier callipers is 0.01 cm and its zero error is
- 0.03 cm. While measuring the length of a
rod, the zero of vernier scale lies between 5.3 cm and 5.4 cm and sixth
division on vernier is in line with a marking on the main scale. Calculate the
length of the rod.
Solution: Length of the rod MSR + VSD x LC = 5.3 cm + 6 × 0.01 cm = 5.36 cm
True length of the rod = observed reading - zero error = 5.36 cm - (-0.03 cm) = 5.39 cm.
Measuring devices:
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| Vernier Caliper L.C= O.01 cm |
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| Ruler L.C= 0.1 cm |
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| Screw Gauge L.C= 0.001 cm Watch this for video visuals: |
