A vernier caliper is defined as a measuring device that is used for the measurement of linear dimensions. It is also used for the measurement of the diameters of round objects with the help of the measuring jaws.

### Vernier Calliper Diagram

French mathematician Pierre Vernier invented the vernier scale in 1631. The main use of the vernier calliper over the main scale is to get an accurate and precise measurement.

## Least Count of Vernier Calliper

The least count of vernier callipers is also known as the vernier constant. It is defined as the difference between one main scale division and one vernier scale division.

It is mathematically given as:

 VC = 1 MSD – 1 VSD

When there are n divisions on the vernier scale which coincides with (n-1) division on the main scale, then the least count of vernier calliper is:

 LC =MSD

Therefore, the least count of vernier calliper is 0.1 mm.

Where,

• VC is the vernier constant
• MSD is the main scale division
• VSD is the vernier scale division
• LC is the least count

### What is Zero Error?

Zero error is defined as the condition in which the measuring device registers a reading when there should not be any reading.

The zero error of vernier calliper is calculated as:

Actual reading = Main scale + Vernier scale – (Zero error)

There are two types of zero error:

• Positive zero error: When the jaws of the vernier calliper are closed and the reading is positive and away from the actual reading of 0.00 mm. For instance, if the reading is 0.08 mm, then the zero error is +0.08 mm.
• Negative zero error: When the jaws of the vernier calliper are closed and the reading is negative and away from the actual reading of 0.00 mm. For instance, if the reading is 0.10 mm, then the zero error is -0.10 mm.

### Solved Examples

Example 1:

If the jaws of the vernier callipers are in contact with each other, then determine the zero error of the vernier calliper if the VSD is 3.

Solution:

Given:

The jaws of the vernier calliper are in contact with each other.

Therefore, the least count of the vernier calliper is given as:

LC = MSD – VSD

LC = 1 – (9/10) = 0.1 mm

The main scale reading, MSR = 0 mm

The vernier scale reading, VSR = 3

Therefore,

Zero error = MSR + VSR x LC

Zero error = 0 + 3 x 0.1 = 0.3 mm

Posted By Simphy / Apr-07-2023