Cany anyone teach me how to use the vernier callipers?

Place the object in between the two jaws such that they touch opposite ends of the object making sure the object is held firmly but don’t press too tight. If you need to measure an internal diameter, then insert the upper jaws in to the cavity and open them till they touch the sides. Tighten the locking screw to hold the jaws in position.

Note the position of the vernier scale zero on the main scale. The main scale reading is the division just before where the zero mark of the vernier scale is aligned. So is the zero mark aligns just after the fifth division between 3 and 4 the main scale reading is then 3.5.

The next step is to take the vernier scale reading. To do this find the mark on the vernier scale which lines up perfectly with a mark on the main scale. The vernier reading can then be found by multiplying the least value of the vernier scale with the number of divisions till that mark. For example if the least value is 0.01 mm and the 7thmark of the vernier scale is lined up perfectly then the vernier scale reading is 7 x 0.01 = 0.07.

The final step is to add the main scale and vernier readings to get the final measurement. For example 3.5 + 0.07 = 3.57 mm.