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## What is the vernier calliper?

It is an instrument used to measure the length,diameter,radius etc.

It can measure up to 1/10 of mm (or 0.1 mm 0.01 cm) which is called least count of Vernier Callipers.

Scales of vernier calliper

- Vernier scale
- Main scale

Main scale is graduated is centimeter while Vernier scale slides along the main scale and is graduated in division (less than millimeter).

## Parts and function of vernier calliper

There are two set of jaws:

- Two jaws
- Main scale
- vernier scale

(1) Lower Jaws:

The lower jaws A and B are used to measure length. Thickness or external diameter of an object.

(2)Upper Jaws:

The upper jaws C and D are used to measure the internal diameter of objects like a hollow cylinder or tube.

The jaws A and B are fixed where B and D are moveable. The moveable jaws are attached to the vernier and they slides along the main scale.

## Vernier Calliper least count

- The smallest reading which can be accurately measured with a vernier callipers is called its least count (L.C).

Find The least count:

First of all find the least count of vernier callipers.(method is given above).

## Vernier calliper zero error

When the jaws of Vernier calippers are brought into contact, the zero of the Vernier must coincide with the zero of the main scale. Otherwise, the instrument has an error called zero error. Zero error can be negative or positive.

Negative Zero Error

If the zero of the Vernier scale is to the left of the zero of the main scale then the error is negative. Since the zero error is negative, the zero correction will be positive.