1. Vernier caliper accuracy: Why does the vernier caliper measure accuracy up to 0.1 mm, or even 0.05 mm, 0.02 mm? The original reason is that the vernier caliper cleverly uses the difference between the minimum scale of the vernier and the main ruler. 10 divisions of mm are used as the scale of the vernier scale, then the difference between the length of each scale on the vernier scale and each scale on the main scale is 0.1 mm. Similarly, if 19 mm, 49 on the main scale mm is divided into 20 parts and 50 parts respectively as 20 scales and 50 scales on the vernier scale, then the difference between the length shown on each scale on the vernier scale and each scale on the main scale is 0.05 mm and 0.02 mm, respectively Therefore, the measurement accuracy of vernier calipers can reach 0.1 mm, 0.05 mm, 0.02 mm.

2. Reading principle: Take a 10-point vernier caliper as an example. Because its accuracy is 0.1 mm, when measuring a length less than 1 mm, the number of tick marks on the vernier ruler is aligned with a certain tick mark on the master ruler. The distance between the zero scale line on the ruler and the zero scale on the vernier scale is a few tenths of a millimeter, and the measured length is a few tenths of a millimeter, as shown in Figure 1-2. The sixth scale line on the vernier scale and the scale on the main ruler Alignment, the measured length is 0.6 mm. When the measurement length is greater than 1 mm, first read the zero scale line on the vernier ruler corresponding to the whole millimeter scale on the main ruler, and then read the vernier ruler to align with the main ruler as described above. The number of scales. After multiplying this number by 0.1, add the two numbers to get the measured length.

The reading of the vernier caliper can be expressed by the formula: x = a + n / b, x is the measured length, a is the main ruler reading, n is the nth tick line where the vernier ruler is coincident with the main ruler, and b is the number of scales on the vernier ruler Note: The reading a must be in millimeters.

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