What is Least Count?

The least count of an instrument is the smallest possible value that can be measured or displayed by the instrument. It represents the precision or accuracy of the instrument. In simpler terms, it is the smallest increment that can be measured or displayed by the instrument.

Why is Least Count Important?

The least count is important because it determines the level of precision in measurements. It helps in determining the accuracy of the instrument and the level of detail that can be observed or measured. The smaller the least count, the more precise the instrument is considered to be.

Calculating the Least Count

The least count of an instrument depends on the instrument's scale and the smallest division on that scale. To calculate the least count, the following steps can be followed:

Step 1: Identify the Scale
Identify the scale or the measuring unit of the instrument. For example, if the instrument measures length, the scale could be in millimeters, centimeters, or meters.

Step 2: Determine the Smallest Division
Determine the smallest division or the smallest increment on the scale that can be measured or observed. This is usually the value between two consecutive markings on the scale.

Step 3: Express the Smallest Division in Terms of the Measuring Unit
Express the smallest division in terms of the measuring unit identified in Step 1. For example, if the smallest division is 0.1 cm, it can be expressed as 0.1 cm or 1 mm.

Step 4: Derive the Least Count
The least count is calculated by taking the reciprocal of the smallest division. In other words, divide 1 by the value obtained in Step 3.

Example Calculation
Let's consider an example to calculate the least count of a Vernier caliper:

Step 1: The scale of the Vernier caliper is in millimeters (mm).
Step 2: The smallest division observed on the scale is 0.02 mm.
Step 3: The smallest division is already expressed in terms of millimeters (0.02 mm).
Step 4: The least count is obtained by taking the reciprocal of 0.02 mm, which is 1/0.02 = 50.

Conclusion

Calculating the least count of an instrument is essential to determine its precision and accuracy. By following the steps mentioned above, one can easily calculate the least count. It is crucial to consider the scale and the smallest division on that scale to derive the least count accurately.