Q. Define Vernier Calliper and describe how it is used to measure length.

 Vernier Caliper

            The Vernier Caliper is a precision instrument that can be used to measure internal and external distance extremely accurate.It has both an imperial and metric scale. A Vernier caliper has main jaws that are used for measuring external diameter, as well as smaller jaws that are used for measuring the internal diameter of objects. Some models also have a depth gauge. The main scale is fixed in place, while the Vernier scale is the name for the sliding scale that opens and closes the jaws.

 

Reading a Vernier Caliper

 

Step 1 Place the object between the jaws of the Vernier caliper

 

Step 2 Note the main scale reading by counting lines before the zero line of Vernier scale

 

Step 3 Count the next line of Vernier scale after zero coinciding main scale

 

Step 4 Add the two reading for total

 

Zero Error The error which arises due to the incorrect gradation of the scales of the verneir calipers is called Zero Error.

 

1. No Zero Error: If the zero of main scale coincide with the zero of the Vernier scale then the instrument has no zero error.

 

2. Positive Zero Error: If the zero of the venier scale on the right of zero of the main scale then the zero error will be positive, but the zero correction will be negative. To find the positive zero error, look at the Vernier scale and not the number of divisions of the venier scale which coincide with one the main scale divisions and multiply this number by least count.

 

3. Negative Zero Error: If the zero of the Vernier scale is one the left of the main scale zero, then the zero error will be negative and zero correction will be positive. To find the zero error note the number of Vernier scale division which coincide with one of the main scale and multiply with least count.