Done by: lim jerome (1O2) 22

1. Measurements of Length Done by: limjerome (1O2) 22

2. Instruments used for measurement of length • Vernier Calipers • Micrometer Screw Gauge • MetreRule

3. Parts of a Vernier Calipers 1. Inside jaws (for measuring internal length measurements.) 2. Retainer or locking screw (blocks movable parts) 3. Vernier scale (inch) 4. Rail (inch) 5. Depth probe (used to find depth) 6. Front end of the rail 7. Main scale (mm) 8. Vernier scale (mm) 9. Sliding jaw 10. Outside jaws (for measuring external length measurements) 11. Fixed jaw

4. Information • Vernier Calipers measure to an accuracy of 0.01cm. • Introduced in 1631 by Pierre Vernier. • Used to measure diameters and thickness of objects.

5. How to use the Vernier Calipers? • First, check for zero errors. • Zero errors are readings that should be zero at the start. • When there is a positive zero error of 0.01cm, subtract 0.01cm from your total length. • When there is a negative zero error, add it to your result.

6. Secondly, put your object in between the jaws of the Vernier Calipers and make sure there are no gaps. jaws object

7. Thirdly, start measuring. • Look at the zero marking on the vernierscale. Take the marking on the main scale that is at the nearest left hand side of the zero markingon the vernierscale. Marking on the main scale

8. Then look at the marking on the vernier scale that is at the same position as the main scale. Markings are at the same positions

9. Lastly, add the first reading and second reading together. First reading(marking on main scale nearest to that of vernier scale). Second reading (markings on vernier and main scale at the same positions). If there is a positive zero error, subtract the error away. If there is a negative error, add it.

10. Parts of a Micrometer Screw Gauge Anvil and spindle - to hold the object tightly Sleeve – where measurements are taken Thimble - to turn till the object is tightly secured for measurements Ratchet - to secure the object firmly between the anvil and spindle Frame - carries the anvil and spindle

11. Information • Micrometer Screw Gauge measures to an accuracy of 0.01mm • Used to measure diameters and length of objects • Introduced in 17th century by William Gascoigne

12. How to use the Micrometer Screw Gauge? • First, check for zero errors. • The procedure of measuring objects using Micrometer Screw Gauge is about the same as the VernierCalipers but the method of measuring is different.

13. Secondly, put the object between the anvil and spindle tightly. object anvil spindle

14. Thirdly, begin measuring. • Look at marking on the sleeve that is nearest to the horizontal line of the thimble. Take the reading in 0.5mm gaps. Take this reading

15. Then read the measurements on the thimble. Take the reading that is in the middle of the vertical line that divides the sleeve into two. Take this reading

16. Lastly add the first and second readings together. First reading(the one on the sleeve). Second reading(the one on the thimble). Then do the changes with the zero errors.

17. MetreRule • It works the same way as a ruler. • It measures to an accuracy of 0.1cm

18. References • http://hyperphysics.phy-astr.gsu.edu/Hbase/Class/PhSciLab/vernier.html • http://everything2.com/title/Zero+error • http://www.measuring-tools.biz/measuring-instruments/parts-caliper.html • http://www.complore.com/using-vernier-calipers-and-micrometer-screw-gauge-0 • http://www.tutorvista.com/content/physics/physics-i/measurement-and-experimentation/screw-gauge.php • http://www.brighthub.com/engineering/mechanical/articles/65356.aspx • http://pachome2.pacific.net.sg/~ezzychan/length.htm

19. Conclusion Measuring instruments such as Vernier Calipers, Micrometer Screw Gauge and the Metre Rule are helpful to us in many ways. Without them, measurements of length and diameter could not be done. We have to thank those people who have invented these useful instruments.

20. The End