Vernier calliper: The vernier calliper is most commonly used for accurate measurements of up to 0.1 mm or 0.01 cm. Vernier calliper consists of a rectangular steel bar whose one side is graduated in Cm's. This scale is the main scale. A small scale consisting of 10 divisions which sliders over the main scale is known the vernier scale.
It has two sets of jaws. which enable it to measure the internal and external diameters of the cylindrical object.
Vernier Constant (VC) or Least Count (LC): The difference between one main scale division and one vernier division is called Vernier constant.
This is the minimum length which can be measured accurately, with the help of a vernier scale. That is why it is called least count of the vernier.
The least count of the vernier is 1-0.9 = 0.1 mm usually the least count is found by dividing the length of one division of main scale by the total number of division on the vernier scale.
10 vernier division = 9 main scale division = 9 mm
1 Vernier division = 9 mm/ 10 = 0.9 mm
Least count = difference between 1 ms division and 1 vs division
= 1 mm - 0.9 mm
= 0.1 mm
= 0.01 cm
The vernier con st can be calculated as follows:
VC = value of the smallest division of MS / Total number of divisions on the VS
= 1 mm/ 10
= 0.1 mm
= 0.01 cm
Zero Error and Zero Correction: On closing the jaws, if the zero of the main scale coincides with the zero of the vernier scale then the instrument has no zero error and no correction is required. Otherwise, there is an error known as the zero error which is equal to the distance between zero of the vernier scale and zero of the main scale.
positive Zero Error:
If the zero of the vernier scale is on the right of the zero of the main scale, the zero error will be positive.
Negative Zero Error:
On closing the jaws if the zero of the vernier scale is on the left of the main scale the zero error is negative.
Thanks Man
ReplyDeleteHi
DeleteHii
ReplyDelete....
ReplyDeleteThanks
ReplyDelete