Vernier Caliper

Vernier Caliper

Vernier Caliper

A vernier caliper is a measuring device used to precisely measure linear dimensions.

It is a very useful tool to use when measuring the diameter of a round objects like cylinders because the measuring jaws can be secured on either side of the circumference.

Vernier calipers have both a fixed main scale and a moving vernier scale.

The main scale is graduated in either millimetres or inch.  

The vernier scale allows much more precise readings to be taken (usually to the nearest 0.02mm or 0.001 inch) in comparison to a standard ruler (which only measures to th nearest 1mm or 0.25 inch).

Uses of a vernier calipers:

Vernier callipers are used to measure,

(i)The length of a rod or any object

(ii)The diameter of a sphere

(iii)The internal and external diameter of a hollow cylinder

(iv)The depth of a small beaker.

Description of vernier callipers:

The main parts of Vernier Callipers are;

1. Main Scale - The main scale is similar to that on a ruler, graduated in mm and cm on one side ; inches on the other side.

2. Vernier Scale – The vernier scale is a sliding scale .It slides parallel to the main scale and enables readings to be made to a fraction of a division on the main scale.

3. Screw -The vernier scale can be fixed at any position on the main scale with the help of a screw.

4. Jaws –It has two jaws. The lower jaws are called outside jaws and they are used to measure the length of a rod, diameter of a sphere or the external diameter of a cylinder. The upper jaws are called the inside jaws which are used to measure the internal diameter of a hollow cylinder or pipe .

5. Strip - The thin strip is used to measure the depth of the objects like beakers.

Least Count of Vernier Caliper:

Least count (L.C.) = 1 M.S.D - 1 V.S.D

In this Vernier caliper one main scale division (49mm) are divided in to 50 equal part in the Vernier scale.

          1 main scale division  (1MSD)          = 1 mm

1Vernier scale division (1VSD)        = 49\50 mm

Least count                              = 1mm – 49\50 mm

                                                                   = (1- 0.98) mm

          Least Count                                       = 0.02mm

How to use a Vernier caliper:

1) The jaws are first gently closed on the object to be measured.

2) Note the main scale reading (M.S.R)

3) Note the division on vernier scale which coincides with any division of the main scale. Multiply this number of vernier division with the least count. This is the vernier scale reading(V.S.R)

Hence V.S.R = Vernier scale Divison x Least count(L.C.)

4) Add the main scale reading to the vernier scale reading. This gives the observed length.

Hence, Observed Reading = Main scale reading + Vernier scale reading

Observed Reading = Main scale reading +( Vernier scale Divison*Least Count)