There is a scale for measuring instruments and the smallest measurement. There is a maximum error in a meter usage. It is the smallest measure of the instrument or a half of the smallest measure.

For example, we consider the Meter Ruler. Learning the use of meters is very important. Its scale is mm, cm. It is 100cm long and divided into 100 parts per 1cm. As 10mm = 1cm. 1m is divided into 1000prts. One part is equal to 1mm. Therefore it’s the smallest measure is 1mm. Did you understand? The maximum error of this ruler is the smallest measure(1mm) or half of smallest measure (0.5mm).

## How to use the meter ruler correctly

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## The accuracy of a measurement

- Partial error of a measure = (Smallest measure of the instrument)/(Length of the measure)
- Percentage error of a measure = [(Smallest measure of the instrument)/(Length of the measure)]*100

In normal use, we rightly consider the measure is accurate only if the percentage error is less than 1 %. If the measurable minimum distance is x mm it’s partial error is 1/x. Now we can find the percentage error by 100 multiplication. Here it is 100/x. This value should be less than 1 to be sufficient in the accuracy. It should be (100/x)< 1. That is, x>100mm. That is, the minimum distance of the measuring line is 100mm. This principle applies to any device. Here you can use 0.5 mm or 1.0 mm as smallest measure.

The Vernier caliper is the same. Its smallest measurement is 0.1mm. The maximum error of this device is 0.1mm. This measuring device measures a minimum distance of 10mm. For the accuracy of the measure, we have to use this method. Here, the minimum distance of the measuring line is 10mm.

### We can conclude what is the minimum distances of the above instruments.

The minimum distance of the measuring line of The Vernier caliper is 10mm. The minimum distance of the measuring line of The meter is 100mm.

### The instrument you have to learn are listed below.

- Meter
- Vernier caliper
- Micrometer screw gauge
- Spherometer
- Travelling microscope
- Tripplebeem balance, Four beam balance, Electronic balance
- Stopwatch, Digital clock.

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