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Home > Education > Vernier Calipers Information

Tips of using the vernier calipers correctly

You can use the vernier calipers to measure lengths much more accurate than the metric rulers.Generally, the smallest increment in the vernier caliper is (1/50)mm=0.02mm=0.002cm.Therefore, the uncertainty is (1/2)0.002 cm=0.001 cm. There are a fixed metric scale and a sliding vernier scale on the vernier scale. The fixed scale is divided into centimeters and millimeters, while the vernier scale is divided so the 50 divisions on it cover the same interval as 49 divisions on the main scale.Therefore, the length of each scale vernier division is 49/50 the length of a main scale division. When you close the jaws completely and note that the first line at the far left on the vernier scale(called the“zero?or“index”line) coincides with the zero line on the main scale. Then you have to carefully compare and you will see that the first vernier division is 0.02 mm short of the first main scale division, the second vernier division is 0.04 mm away from the second main scale division. If the jaws are slightly opened and it is easy to tell what fraction of the main scale division the vernier index has moved by noting which vernier division best coincides with a main scale division. A measurement is made with a vernier caliper by closing the jaws on the object to be measured and then reading the position where the zero line on the vernier falls on the main scale.The measurement is incomplete until an additional fraction of a main scale division is determined.This is obtained by noting which line on the vernier scale(0,2,4,6,8) coincides best with a line on the main scale. Just take measuring the length of the aluminum block for an example. It is very important for us to note that the zero line on the vernier scale falls between the 4.4 cm and 4.5 cm mark on the main scale. So the first significant digits are 4.4 cm.The remaining two digits are obtained by noting which line on the vernier scale(0,2,4,6,8)coincides best with a line on the main scale. You can see that the 46 line lines up the closest.Therefore, the reading is 4.446 cm. Or in standard form 4.446 cm±0.001 cm.