Micrometer JavaScript HTML5 Applet Simulation Model

For Students

  A micrometer reading contains two parts:

• the first part is contributed by the main scale on the sleeve
• the second part is contributed by the rotating vernier scale on the thimble

To obtain the first part of the measurement: Look at the image above, you will see a number 5 to the immediate left of the thimble. This means 5.0 mm. Notice that there is an extra line below the datum line, this represents an additional 0.5 mm. So the first part of the measurement is 5.0+0.5=5.5 mm. To obtain the second part of the measurement: Look at the image above, the number 28 on the rotating vernier scale coincides with the datum line on the sleeve. Hence, 0.28 mm is the second part of the measurement. You just have to add the first part and second part of the measurement to obtain the micrometer reading: 5.5+0.28=5.78 mm.

The image shows a typical micrometer screw gauge and how to read it. Steps:

• To obtain the first part of the measurement: Look at the image above, you will see a number 5 to the immediate left of the thimble. This means 5.0 mm. Notice that there is an extra line below the datum line, this represents an additional 0.5 mm. So the first part of the measurement is 5.0+0.5=5.5 mm.
• To obtain the second part of the measurement: Look at the image above, the number 28 on the rotating vernier scale coincides with the datum line on the sleeve. Hence, 0.28 mm is the second part of the measurement.

You just have to add the first part and second part of the measurement to obtain the micrometer reading: 5.5+0.28=5.78 mm.
To ensure that you understand the steps above,

First part of the measurement: 2.5 mm Second part of the measurement: 0.38 mm Final measurement: 2.88 mm

here’s one more example:
First part of the measurement: 2.5 mm
Second part of the measurement: 0.38 mm
Final measurement: 2.88 mm

micrometer with +1 mm zero error

Now, we shall try with zero error.
The reading on the bottom is the measurement obtained and the reading at the top is the zero error. Find the actual measurement. (Meaning: get rid of the zero error in the measurement or take into account the zero error)

Measurement with zero error: 1.76 mm Zero error: + 0.01 mm (positive because the zero marking on the thimble is below the datum line) Measurement without zero error: 1.76–(+0.01)=1.75 mm

Measurement with zero error: 1.76 mm
Zero error: + 0.01 mm (positive because the zero marking on the thimble is below the datum line)
Measurement without zero error: 1.76–(+0.01)=1.75 mm

Pictures