Precise results when it is necessary to make more

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precise results. When it is necessary to make more precise linear measurements, you must have a more precise instrument. One such instrument is the vernier caliper. The vernier caliper was introduced in 1631 by Pierre Vernier. It utilizes two graduated scales: a main scale similar to that of a ruler and a especially graduated auxiliary scale, the vernier, that slides parallel to the main scale and enables readings to be made to a fraction of a division on the main scale. With this device you can take inside, outside, and depth measurements. Some vernier calipers have two metric scales and two English scales. Others might have the metric scales only. 67
Fig. 3 - Vernier caliper with closed jaws Notice that if the jaws are closed, the first line at the left end of the vernier, called the zero line or the index, coincides with the zero line on the main scale (Fig. 2). The least count can be determined for any type of vernier instrument by dividing the smallest division on the main scale by the number of divisions on the vernier scale. The vernier caliper to be used in the laboratory measurements has a least count 0.02mm. Instructions on how to read the measurements on this particular model can be found in: The link below has a caliper simulator, practice with it before the lab session: - mm.html For our experiment will be using a caliper with English and Metric scales. The top main scale is English units and the lower main scale is metric. For our experiment will be concentrating on metric only. In our model the metric scale is graduated in mm and labeled in cm. That is, each bar graduation on the main scale is 1mm. Every 10 th graduation is numbered (10mm). The vernier scale divides the millimeter by fifty (1/50), marking the 0.02mm (two hundredths of a millimeter), which is then the least count of the instrument. In other words, each vernier graduation corresponds to 0.02mm. Every 5 th graduation (0.1mm) is numbered. Having first determined the least count of the instrument, a measurement may be made by closing the jaws on the object to be measured and then reading the position where the zero line of the vernier falls on the main scale (no attempt being made to estimate to a fraction of a main scale division). We next note which line on the vernier coincides with a line on the main scale and multiply the number represented by this line (e.g., 0,1,2, etc.) by the least count on the instrument. The product is then added to the number already obtained from the main scale. Occasionally, it will be found that no line on the vernier will coincide with a line on the main scale. Then the average of the two closest lines is used yielding a reading error of approximately 0.01mm. In this case we take the line that most coincides.

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