Lecture-2| Units & Measurement

Measurement:

Measurement is the most important aspect of this chapter. There are various types of measurements such as, Measurement of length, mass, temperature, time etc.

To understand measurement in simplest way we shall begin with the measurement of length first. For any measurement the instrument is the most important factor. The instruments are elected based on the requirement of measurements i.e., least count of measurement. 

Least Count  (LC): It is the smallest measurement that can be done by an instrument.

We shall take various instruments used for measurement of length and evaluate their least counts(LC).

We have listed some instruments used for measurement of length and their least counts. 

In general the lest count for instruments are as follows :

1. Meter Scale
   • Least Count: L.C. = 1 mm
2. Vernier Caliper
   • Least Count: L.C. = 0.1 mm
   • Some vernier calipers have: L.C. = 0.05 mm
3. Micrometer Screw Gauge
   • Least Count: L.C. = 0.01 mm

 Vernier calipers : 

Least Count of Vernier Caliper

\(\,\text{MSD}-1\,\text{VSD}=\text{Least Count}\)

\(\text{Least Count} = \frac{\text{Smallest division on Main Scale}} {\text{Total divisions on Vernier Scale}}\)

For 20 vernier-scale divisions:

\(\text{Least Count}=\frac{1\,\text{mm}}{20}=0.05\,\text{mm}\)

For 10 vernier-scale divisions:

\(\text{Least Count}=\frac{1\,\text{mm}}{10}=0.1\,\text{mm}\)