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Measurement and Measuring Instruments

Measurement of Length- Lab Method

Vernier Calliper

For measuring length of a rod, diameter of a sphere, depth of small bottle, etc., vernier calliper is used. Vernier calliper was invented by Pierre Vernier. It has an accuracy up to 0.01 cm.

PrincipleThe vernier calliper consists of two scales: main scale with jaw J1 and vernier scale with jaw J2.  The main scale is graduated with division of 1 mm each. The vernier scale graduation is such that the length of n division on it is equal to the (n-1) divisions of the main scale. The vernier scale can slide over the fixed main scale such tha the vernier scale can be fixed at any position on the main scale with the help of a screw S.

Essential Parts:

  1. Main Scale

It is a thin long strip of steel on which a scale in engraved in mm. The main scale is generally 15 cm long.

  1. Vernier Scale

It is a small movable scale, which slides along the main scale. It has 10 divisions adding up to 9 mm length.

  1. External jaws

J1 and J2 are called external jaws because they are used for measuring external dimensions.

  1. Internal jaws

J3 and J4 are collectively called internal jaws and are used for measuring internal dimensions of a hollow object.

  1. Tail

It is at the end of main scale and slides along with the Vernier scale.

When jaws J1 and J…

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