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The origin of callipers goes back to the ninth A.D Qin dynasty. The second addition to reduce the error rate was that of a vernier calliper made in 1631 by the French mathematician Pierre Vernier.
The main use of vernier callipers is to measure internal and external dimensions or distances with extreme precision. Vernier callipers are preferable to other flat devices like rulers because they have an extremely small reading error of 0.05 mm, which is about 0.0019 inches.
Vernier caliper types
There are basically three vernier calliper types used in physics which are as given below.
Type A
Type B
Type C
There are two vernier callipers types in which one is manual which has two scales, one empirical and one metric, and the other is a digital calliper which has an LCD display that shows the reading. Manual callipers are still preferred by people as they are much cheaper than digital callipers and are not performance dependent.
A vernier calliper is a measuring device which is used for the determination of linear dimensions. Vernier calliper is also used for the calculation of diameters of circular bodies with the help of the measuring jaws.
Least Count of Vernier Caliper
The least count of vernier callipers is also termed as the vernier constant. Vernier Calliper is the difference between main scale division and vernier scale division.
Least count of vernier calliper is given as
Thus, the least count of vernier callipers is 0.1 mm.
Here,
VC = vernier constant
MSD = main scale division
VSD = vernier scale division
LC = least count
How To Read Vernier Caliper
First step is to measure nothing through which we can check when the main scale and the vernier scale are aligned with one another.
When the reading of the main scale and the reading of vernier scale are at zero, then there is no any zero error.
Place a ball between the two jaws of vernier scale.
Observe 0 mark on vernier scale lining with main scale.
It gives main scale reading.
Now observe the point on the vernier scale that is aligned with the main scale and which gives the reading of the vernier scale.
It is necessary to note that the readings should be in decimals form.
The number which is before the decimal point is the reading of the main scale and the number after the decimal point is the reading of the vernier scale.
Main Scale
Main scale is a big scale which runs through the body of the vernier calliper. The main scale reading can either be in centimetres or millimetres that depend on the usage. According to the SI units 1 mm is the smallest division of main scale.
Lower Jaws
Lower jaws are one of the most important features of vernier calliper. There are two jaws in which one jaw is fixed and attached to the main scale. And the other jaw is movable which is connected to the vernier scale. Lower jaws are formed basically to grip the objects firmly. The main function of the lower jaw is to determine the outer dimensions like diameter, width and length.
Upper Jaws
Upper jaws are similar to the lower jaws but the only difference is that the upper jaws are smaller than the lower jaws. Upper jaws are connected to the upper part of the vernier scale. One of the jaws is static and the other jaw can move. The main function of the upper jaw is to determine the inner dimensions of objects. Jaws are opened till they touch the edge of the objects before taking the reading. The inner diameters of objects like hollow pipes and jars can be determined using upper jaws.
Using the Vernier Caliper
As mentioned above, the vernier calliper has two jaws. The larger one is squeezed around the object while the smaller one is inserted into the opening. The larger jaws are used to measure the distance between two ends, while the smaller jaws are used to measure the inner diameter. Both pairs of jaws work by sliding the small scale.
When the zero of the sliding scale (vernier scale) coincides with the main scale, the student must write down the number on which it is zero. The scale is read like a ruler and when the result is between two values, use the lower one.
Reading on the vernier calliper scale is the mark on the vernier scale which matches with its main scale counterpart.
The main scale reading and vernier calliper scale reading is added to get the final answer.
Conclusion
A Vernier Callipers is a measuring device which is used for the determination of linear dimensions. Vernier calliper is also used for the calculation of diameters of circular bodies with the help of the measuring jaws.
There are two vernier callipers types in which one is manual calliper and digital calliper.
Least count of vernier calliper is given as
