The line labeled 0 is the primary pointer. When it lines up with the central horizontal line on the cylinder, as shown, then the distance between the measuring rods is exactly an integral or half-integral number of millimeters.
The left-hand side of the thimble has markings all around it.
3) In this case, then, the distance between the measuring rods is 7.000 mm . The upward line on the cylinder corresponding to 7 mm is barely visible under the thimble.
Primary pointer Central horizontal line 1 2 3 4 6 7 0.5 1.5 2.5 3.5 4.5 5.5 6.5
Report to 3 decimal places. Your instrument is capable of reading up to thousandths of a millimeter. ( That is why it is called a micrometer, 10 -6 of a meter).
1) If we rotate the thimble one complete revolution so it moves to the right, it will look as shown. 2) Now the distance between the measuring rods is 7.500 mm. The downward line on the cylinder corresponding to 7.5 mm is barely visible. 3) Note that this is all consistent with the fact that the markings on the cylinder correspond to fifty divisions for a complete revolution. Thus the numbers on the thimble correspond to hundredths of a millimeter. 7 7.5 7.5+0.000 = 7.500 mm
Depending on your eyes and screen resolution, you might be fairly confident that the reading is less than, say, 8.627 mm and similarly confident that it is greater than 8.621 mm. Thus you might assign a Reading Error to this measurement of 0.003 mm
So, we would report the distance as 8.624 ± 0.003 mm.
In figure 4 above, the first significant figures are taken as the main scale reading to the left of the vernier zero, i.e. 3.7 cm. The remaining digits are taken from the vernier scale reading that lines up with any main scale reading, (i.e. 0.46 mm or 0.046 cm) on the vernier scale. Thus the reading is 3.746 cm.
In figure above, the first significant figures are taken as the main scale reading to the left of the vernier zero, i.e. 3.4 cm. The remaining digit is taken from the vernier scale reading that lines up with any main scale reading, (i.e. 0.60 mm or 0.060 cm) on the vernier scale. Therefore the reading is 3.460 cm.
In figure 6 the zero and the ten on the vernier scale both line up with main scale readings, therefore the reading is 4.000 cm.
Okay, that is enough! Let us try to apply it in real life.
Try to measure the quantities of the following objects. Fill-out the table below. Quantities to Measure Micrometer Vernier Caliper 1) Diameter of a 1-peso coin 2) Thickness of a 5-peso coin 3) Thickness of your hair