# Describe in steps, how would you use a vernier callipers to measure the length of a small rod?

In order to measure the length of a small rod, we follow the following steps:

1. Find the least count and zero error of the vernier callipers.
2. The rod is placed between the fixed end and the vernier scale as shown in the diagram.
3. Note the main scale reading.
4. Note that division p on the vernier scale which coincide or is in line with any division of the main scale. Multiply this vernier division p with the least count. This is the vernier scale reading i.e., Vernier scale reading = p x L.C.
5. Repeat it two times and record the observation.

Observations —

Total number of divisions on vernier scale (n) = ………..

Value of one division on the main scale (x) = ……….. cm

Least count (L.C.)=xn=……….cm

Zero error = ……. cm

S No. The main scale reading a (in cm) Vernier division coinciding (p) Vernier scale division b = p x L.C.(in cm) Observed length = a + b (in cm)
(1)
(2)
(3)

Mean observed length = ……… cm

From the mean observed length, subtract zero error, if any, with its proper sign to obtain the true measurement of the length of the given project.

Thus we get,

Observed length = main scale reading + (vernier division p coinciding with any division on the main scale) x least count.

True length = observed length – zero error (with sign).

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