If 50 Vernier divisions are equal to 49 main scale divisions of a travelling microscope and one smallest reading of the main scale is 0.5 mm, the Vernier constant of the travelling microscope is:
The Vernier constant (VC) is calculated as:
\[ \text{VC} = \text{Value of 1 MSD} - \text{Value of 1 VSD} \]
Given that 50 Vernier divisions correspond to 49 main scale divisions:
- The value of 1 MSD is 0.5 mm.
- Therefore, the value of 1 VSD is:
\[ \text{Value of 1 VSD} = \frac{49 \times 0.5 \text{ mm}}{50} = 0.49 \text{ mm} \]
Calculating the VC:
\[ \text{VC} = 0.5 \text{ mm} - 0.49 \text{ mm} = 0.01 \text{ mm} \]
Figure 1 shows the configuration of main scale and Vernier scale before measurement. Fig. 2 shows the configuration corresponding to the measurement of diameter $ D $ of a tube. The measured value of $ D $ is:
A unit of a physical quantity is an arbitrarily chosen standard that is broadly acknowledged by the society and in terms of which other quantities of similar nature may be measured.
The process of measurement is basically a comparison process. To measure a physical quantity, we have to find out how many times a standard amount of that physical quantity is present in the quantity being measured. The number thus obtained is known as the magnitude and the standard chosen is called the unit of the physical quantity.
Read More: Fundamental and Derived Units of Measurement
The units defined for the fundamental quantities are called fundamental units.
The units of all other physical quantities which are derived from the fundamental units are called the derived units.