In physics laboratories, a standard ruler can only measure down to 1 millimeter. To measure extremely tiny objects (like the thickness of a wire or inner diameter of a pipe) with high accuracy, we use a Vernier Caliper. To use it, you must first calculate its 'Least Count'.
A standard vernier caliper is exactly 10 times more accurate than a normal geometry box ruler.
For highly advanced industrial vernier calipers, the vernier scale might have 50 divisions, making the Least Count 0.02 mm.
The Least Count (LC) of any measuring instrument is the absolute smallest measurement that can be accurately read using that instrument. For a Vernier caliper, it is also known as the Vernier Constant.
The Least Count is calculated using the difference between the main scale and the vernier scale: Least Count (LC) = 1 Main Scale Division (MSD) - 1 Vernier Scale Division (VSD)
Alternatively, a much easier formula is: LC = (Value of 1 Smallest Division on Main Scale) / (Total Number of Divisions on Vernier Scale)
Let's calculate it for a normal school laboratory Vernier Caliper:
A micrometer screw gauge is even more sensitive. Its standard Least Count is usually **0.01 mm** (or 0.001 cm).
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