Presented by: Riel M. Casinillo

Faculty

MeasurementMeasurementand Measuring Devicesand Measuring Devices

(Micrometer and Vernier Caliper)(Micrometer and Vernier Caliper)

What are we going to do today?What are we going to do today?

1) We are going to read and use the 1) We are going to read and use the following instruments in measuring following instruments in measuring certain quantities:certain quantities:

MicrometerMicrometer Vernier CaliperVernier Caliper

The MicrometerThe Micrometer

A A micrometermicrometer allows a measurement of the size allows a measurement of the size of a body. It is one of the most accurate of a body. It is one of the most accurate mechanical devices in common use.mechanical devices in common use.

Parts of a Micrometer

How to read and use the How to read and use the Micrometer?Micrometer?

1) 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.

2)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 1.52.5

3.54.5

5.56.5

Remember!!!Remember!!!

Report to 3 decimal places. Your Report to 3 decimal places. Your instrument is capable of reading up to instrument is capable of reading up to thousandths of a millimeter. ( That is why thousandths of a millimeter. ( That is why it is called a micrometer, 10it is called a micrometer, 10-6 -6 of a meter).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

One more complete revolution takes the One more complete revolution takes the distance to distance to 8.0008.000 mm, as shown. mm, as shown.

8

0.000

8.000 mm + 0.000 mm = 8.000 mm

Now turn the thimble just a little bit more, and Now turn the thimble just a little bit more, and end up with the situation shown.end up with the situation shown.

We have increased the distance by 0.120 mm We have increased the distance by 0.120 mm from 8.000, so the distance between the from 8.000, so the distance between the measuring rods is now measuring rods is now 8.1208.120 mm. mm.

8

0.120 mm

8.000 mm + 0.120 mm = 8.120 mm

If we give the thimble one complete further rotation, If we give the thimble one complete further rotation, we end up with the micrometer as shown above.we end up with the micrometer as shown above.

Now the distance is 0.120 mm greater than Now the distance is 0.120 mm greater than 8.5008.500 mm, so the distance is mm, so the distance is 8.6208.620 mm. mm.

8.5 mm

0.120 mm

8.500 mm + 0.120 mm = 8.620 mm

Finally, if we turn the thimble a tiny bit further, Finally, if we turn the thimble a tiny bit further, it might end up like the figure above.it might end up like the figure above.

Now the distance is greater than 8.620 mm, but Now the distance is greater than 8.620 mm, but clearly less than 8.630 mm. We might estimate clearly less than 8.630 mm. We might estimate this reading to be this reading to be 8.6248.624 mm. mm.

8.5 mm

0.120 mm

8.500 mm + 0.124 mm = 8.624 mm

Depending on your eyes and screen resolution, Depending on your eyes and screen resolution, you might be fairly confident that the reading is you might be fairly confident that the reading is less than, say, 8.627 mm and similarly confident less than, say, 8.627 mm and similarly confident that it is greater than 8.621 mm. Thus you might that it is greater than 8.621 mm. Thus you might assign a assign a Reading ErrorReading Error to this measurement of to this measurement of 0.003 mm0.003 mm

So, we would report the distance as So, we would report the distance as 8.624 ± 8.624 ± 0.0030.003 mm. mm.

Let us try!!!Let us try!!!

1)

Answer: 7.880 mm

2)

Answer: 7.721± 0.003 mm

3)

Answer: 3.560 mm

4)

Answer: 5.801 ± 0.003 mm

5)

Answer: 3.090 mm

Zero errorZero error

The Vernier CaliperThe Vernier Caliper This instrument may be used to measure outer This instrument may be used to measure outer

dimensions of objects (using the main jaws), dimensions of objects (using the main jaws), inside dimensions (using the smaller jaws at the inside dimensions (using the smaller jaws at the top), and depths (using the stem). top), and depths (using the stem).

How to read and use the How to read and use the Vernier Caliper?Vernier Caliper?

The reading here is 3.7 mm or 0.37 cm.

The reading here is 15.8 mm or 1.58 cm.

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.

Let us try!!!Let us try!!!

1)

Answer: 3.090 cm

Answer: 0.810 cm

2)

3)

Answer: 12.168 cm

Zero ErrorZero Error

Okay, that is enough!Okay, that is enough!

Let us try to apply it in Let us try to apply it in real life.real life.

Try to measure the quantities of the Try to measure the quantities of the following objects. Fill-out the table following objects. Fill-out the table

below.below.

Quantities to Quantities to MeasureMeasure

MicrometerMicrometer Vernier Vernier CaliperCaliper

1) Diameter of 1) Diameter of a 1-peso coina 1-peso coin

2) Thickness of 2) Thickness of a 5-peso coina 5-peso coin

3) Thickness of 3) Thickness of your hairyour hair

Give me a reading of:Give me a reading of:

5.66 cm5.66 cm 4.78 cm4.78 cm