Length Measurement
To measeure the length of a thing, you can use ruller, roll metre (pedometer), vernier caliper, or micrometer caliper. Can all of tools of length measurement be used to measure anything ? For example to measure the diameter of a wire can you use a ruler and to measure a length of a bench, can you use a vernier caliper ? To use measure a length of a thing, you have to choose the appropriate tool.
1. Ruler
To measure a length or wide a book, you can use a ruler. There are two kinds of scales in a ruler; there are milimetre (mm) for small ruler and centimetre (cm) for a ruler with 1 metre length or in pedometer. The accuracy of measurement using ruler is 0.5 mm.
This value is obtained from a half the smallest scale on the ruler that is 1 mm. To measure a length of ground, a yard, or road, we use pedometer that have the smallest scale of 1 cm. It means that the precision of the pedometer is 0.5 cm.
2. Vernier Caliper
In craftmanship or machinery, the use of vernier caliper is very important. To measure the diameter of a pipe, both inside diameter and outer diameter, it will be appropriate if you use vernier caliper. There are two kinds of vernier caliper that you can meet in markets, they are vernier caliper with the precision of 0.1 mm and 0.05 mm. Vernier has two important parts, they are
- Fixed jaw, it has the main scale (in cm)
- Sliding jaw, it has vernier scale (in mm)
For vernier caliper with the precision of 0.1 mm, the length of vernier scale is 9 mm divided into 10 parts. Beside the vernier caliper with the precision of 0.1 mm, people also use the vernier caliper woth the precision 0.05 mm. On this kind of vernier caliper, the length of vernier scale is 39 mm, divided into 20 scale.
How To Use Vernier Caliper
The result of measurement using vernier caliper with the precision of 0,1 mm shown above is
- Main scale = 2.4 cm
- Vernier Scale = 0.07
- Measurement Result = 2.47
3. Micrometer Caliper
To measure the thing with precision of 0.01 mm, we use micrometer caliper. Tool that is used to measure the thickness of a paper, slight metal, or diameter of wire is micrometer caliper.
How to Use Micrometer Caliper
Put the thing you want to measure between the sliding jaws, next turn the big turning until both jaws touch the thing. And then, turn the small turning until the number in the vernier scale (big turning) cannot shift again. Then result can be obtained by reading the number in the main scale added by the number in the turning scale.
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