What is the principle of a vernier caliper?

The principle of a vernier caliper is actually very simple; you can understand it once you take one and look at it. There’s no need for anyone to introduce you at all.

Both the scale body and the vernier scale are marked with scales. Taking a vernier caliper accurate to 0.1 millimeters as an example, the smallest division on the main scale is 1 millimeter. The vernier scale has 10 small equal divisions, with a total length of 9 millimeters; each division therefore corresponds to 0.9 millimeters, which is 0.1 millimeter less than the smallest division on the main scale. When the jaws are closed, the zero marks on the scale body and the vernier align with each other. The first scale marks differ by 0.1 millimeters, the second by 0.2 millimeters, and so on; the 10th scale mark differs by 1 millimeter, meaning that the 10th mark on the vernier aligns precisely with the 9-millimeter mark on the main scale. 　　When the dimension of the object measured between the equivalent jaws is 0.1 millimeter, the vernier scale should move 0.1 millimeter to the right. At this point, its first scale line aligns precisely with the 1-mm scale line on the ruler body. Similarly, when the fifth scale line of the cursor aligns with the 5-millimeter scale line on the scale body, it indicates that there is a width of 0.5 millimeters between the two jaws, … and so on. (baidu);P

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