Vernier Caliper Standard Practices for Reading its Scales

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Definition: The Vernier Caliper is an instrument used widely to measure lengths accurately up to 0.01 cm. It enables us to measure lengths much more accurately than a simple ruler and can be used to measure the diameter of a round object, the inside diameter of hollow vessels or pipes and even the depth of vessels.

Vernier caliper parts

Vernier Caliper Parts and Scales: The vernier caliper consists of two scales. One is the fixed scale which is calibrated in centimeters while the second scale is the vernier scale or the sliding scale because it slides along the main scale. This vernier scale is responsible for lending accuracy to the vernier caliper. Two sets of jaws are attached to the vernier caliper for gripping objects which need to be measured. The lower jaws are used to measure the outer diameters of circular objects while the upper jaws are used to measure internal diameters.

Vernier Caliper Standard Practice to Read and Measure: The vernier caliper is a precise instrument which can measure lengths with an accuracy of 0.01 cm or 0.1 mm. To measure an object the following steps should be followed:

1. Grip the object lightly between the jaws(lower for external and upper for internal diameters

2. Take the reading on the main scale directly to the left of the zero mark on the vernier scale

3. Find the mark on the vernier scale which coincides directly with the main scale

4. Now add this reading to the main scale reading to find the required length.

The least count is the smallest reading you can measure on a scale. It is found by dividing the unit measurement on the scale by the number of divisions in between. For example the unit measurement on the main scale is 1 cm and if there are 10 divisions between a cm then the least count will be 1/10= 0.1cm.

vernier-caliper main scale

Similarly the least count of the vernier caliper can be calculated by dividing the least count of the main scale by the number of divisions on the vernier scale. This way if there are 10 divisions on the vernier scale then the least count would be 0.1/10= 0.01 cm.

The total reading can then be found by the following formula:

Total Reading= Main Scale reading + Vernier reading x least count

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