🌈 Vernier Calipers

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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: 

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.

 

Negative Zero Error

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:

 

Vernier Caliper
L.C= O.01 cm

Ruler
L.C= 0.1 cm

Screw Gauge 
L.C= 0.001 cm

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