Measuring Length: Ruler, Caliper, and Micrometer

In Physics certainly can not be separated from measurement activities. Measuring activities require appropriate measuring tools. The accuracy of the measurement results is determined by the type of tool used. The use of a certain type of measuring instrument is determined by several factors, namely: the accuracy of the desired measuring results, the size of the measured amount, and the shape of the object to be measured.

Ruler / ruler, slide calipers, and micrometer screws are examples of length measuring devices. Each measuring instrument has a different accuracy, so you should be able to choose the right measuring instrument for a measurement. Selection of measuring instruments that are not right will cause errors in the measurement results.

1. Ruler (Ruler)

Ruler or ruler is a length measuring instrument that is often used. This measuring instrument has the smallest scale of 1 mm or 0.1 cm. The ruler has a measurement accuracy of half of its smallest scale of 0.5 mm. When measuring with the ruler, the direction of view must be perpendicular to the scale on the ruler and the object being measured. If it is not perpendicular it will cause an error in the measurement, it can be bigger or smaller than the original size.

Example:

 

2. Calibration term

Caliper is also a measuring device of length and is commonly used to measure the diameter of an object. The inventor of the calipers was a French engineer Pierre Vernier. The calipers are made up of two parts, the fixed jaw and the sliding jaw. The long scale on the fixed jaw is the main scale , while the short scale on the sliding jaw is the nonius or vernier scale , taken from the name of the inventor. The main scale has a scale in cm and mm. While the nonius scale has a length of 9 mm and is divided by 10 scales. So the difference between one nonius scale and one scale on the main scale is 0.1 mm or 0.01 cm. So, the smallest scale on the calipers is 0.1 mm or 0.01 cm.    

Example:

Figure (a) shows the parts of the calipers and Figure (b) shows the calipers scale.

The length of the object is measured by the calipers shown in figure (b). In the picture above the main scale (sku) 62 scale and nonius scale (skn) 4 scale. So that we can know the length of the object measured in the following way:

Length of object = sku. 1 mm + skn. 0.1 mm

                        = 62. 1 mm + 4. 0.1 mm

                         = 62 mm + 0.4 mm

                         = 62.4 mm

3. Micrometer Screw

Micrometer screw is used to measure thin objects, such as paper thickness and hair diameter. Micrometer screw consists of two parts, namely the sheath (fixed shaft) and the outer sheath (screw shaft). The length scale on the shaft remains the main scale , whereas on the screw shaft it is a nonius scale . The main scale of the micrometer screw has a scale in mm, while the nonius scale is divided into 50 parts. One section on the nonius scale has a value of 1/50 × 0.5 mm or 0.01 mm. Thus, the screw micrometer has a higher accuracy than the two tools previously mentioned, which is 0.01 mm.  

Example:

 

On the screw micrometer above, it is shown that sku = 9 scale and skn = 43 scale, then the length of the object measured can be determined in the following manner:

The length of the object = (sku. 0.5 + skn. 0.01) mm

                         = (9. 0.5 + 43. 0.01) mm

                         = (4.5 + 0.43) mm

                        = 4.93 mm

, make it easy to count with the bar, calipers and micrometers. I hope this article is useful. Thank you and best regards