Measuring Instruments

Course: DiplomaSubject: Applied Science Physics

Unit: IChapter: III

Use of Vernier Caliper

Vernier Caliper can be used to measure diameter, thickness very accurately.

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0 cm 2 cm1 cm

0 10

Main Scale

Vernier Scale

Main Scale

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Vernier Scale4

How to read the result

of measuring by using

the Vernier caliper

What is the result of measuring ?5

What does it mean ?

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6 mm

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What does it mean ?8

( 2 x 0.1 ) mm9

6 mm

( 2 x 0.1 ) mm

The result of measuring is ( 6 mm + 0.2 mm ) = 6.2 mm

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What is the result of measuring ?

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The result of measuring is :

( 3 mm + ( 7 x 0.1 ) mm ) = 3.7 mm

0 cm 2 cm1 cm

0 10

Main Scale

Vernier Scale

X 0.1 mm

Least Count = Value of the smallest division on MS/ Total number of division on VS

L.C = 1mm / 10 = 0.1 cm / 10 = 0.01cm

0 cm 2 cm1 cm

0 4 8 6 2 10

Main Scale

Vernier Scale

X 0.05 mm

Measuring Internal Diameter

Use the inside jaws of the caliper as shown

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Measuring External Diameter

Use the outside jaws of the caliper as shown

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Measuring Height of Bar.

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Measuring Depth of a Hole

Use the depth gauge of the caliper as shown

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Measuring Instruments

• Vernier Caliper•   (a) Positive zero error• Zero error = +0.04 cm.

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Measuring Instruments

• Vernier Caliper

(b) Negative zero error• Zero error = -0.02 cm.

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Structure of the Micrometer

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Scale description : Main scale & Circular scale

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Least Count• Least Count = Pitch of the Micrometer / Total

number of circular scale division• Least Count = 1 / 100 = 0.01mm

= 0.001cm

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Measuring Instruments

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Dial Caliper The dial Caliper has seven main components: a slide scale, lock screw, thumb adjustment wheel, measuring jaws (inside & out), dial with measurements of 0.001 inch, depth rod and a bezel.23

Dial CaliperTry this one

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Dial Caliper

• Answer is • 1.931

Read the Measurement 1

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Read the Measurement 2

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Read the Measurement 3

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Read the Measurement 4

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Read the Measurement 5

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Description of the Spherometer

• Instrument that measures the surface power (D) associated with the lens surfaces.

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Functional Principle

Supporting the legs on the lens surface, the movement of the center leg, is translated to the scale, giving the value of the surface power of the surface.

Positive value in convex surfaces.

Negative value in concave surfaces.

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Zero errorAdjustment or Calibrating the instrument to zero:

When placing the instrument on a flat polished surface, the scale must mark 0.00 D.

If not, all previous measurements will be affected by this value.

The measurement will be a result of the following equation:

Psur: Value given by spherometer when place on flat surface.

Psph: Value given by spherometer when placed on one of the curved surfaces of the lens.

surPspherePP

A thermometer is an instrument that is used to

measure temperature.

The temperature tells us how hot or cold something is.

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Temperature is measured using two scales: Celsius and Fahrenheit.

212100 C F

Galvanometer

• The galvanometer is the "classic" device to measure current

• Based on the fact that a wire carrying current in a magnetic field feels a force

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• The current flows through a coil in a magnetic field

• The coil experiences a torque proportional to current

• The movement of the coil is "opposed" by a spring

• The deflection of the needle is proportional to current

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• Rsh = "shunt" resistance

• The current I divides itself between the coil and the shunt– I = IC + Ish

• By Ohms's law, Vab = IC RC = Ish Rsh

• Ish = IC (RC/Rsh)• I = IC + Ish = IC (1 + RC/Rsh) If RC and Rsh are known, measuring IC is

equivalent to measuring I• Furthermore, I is still proportional to IC, which is

proportional to the deflection of the needle• Thus, by "switching in" different shunt resistances I

can effectively change the "range" of my current measurement

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Electrical Measuring Instruments Ammeter

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Electrical Measuring Instruments

Voltmeter

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4349

5352

5051

REFERENCE BOOKS AUTHOR/PUBLICATION

ENGINEERING PHYSICS S S PATEL (ATUL PRAKASHAN)

MODERN ENGINEERING PHYSICS

A S VASUDEVA

ENGINEERING PHYSICS K. RAJGOPALAN

Image reference links1. http://www.slideshare.net/stootypal/vernier-caliper2. http://www.tutorvista.com/content/physics/physics-i/measurement-and-experimentation/vernier-calliper

s.php

3. To 11) http://i.imgur.com/2QqIQsU.png12. http://postimg.org/image/56z59zrtp13. http://postimg.org/image/hkbzgwhi514. http://www.muelaner.com/wp-content/uploads/2013/07/Calipers-Bolt2.png15. http://postimg.org/image/8f3mn1e3h16. http://i.imgur.com/V5pHuiR.png17. http://i.imgur.com/7TShrLa.png18. http://www.technologystudent.com/equip1/microm1.htm 19. http://www.indiastudychannel.com/attachments/Resources/143680-5126-Micrometergauge.jpg20. http://www.cyberphysics.co.uk/practical/skills/micrometer2.gif21. http://i.imgur.com/cxlIcvh.png22. http://www.tutorvista.com/content/physics/physics-i/measurement-and-experimentation/screw-gauge.ph

p

23. http://0801.nccdn.net/1_5/2ff/292/391/dial-calipers.png24. http://www.pixentral.com/pics/1CpY49KAqUFdhu88HhJTCL87z92J.png25. http://i.share.pho.to/1b2ffae6_o.png26. http://i.share.pho.to/dc6d8ee9_l.png27. http://i.share.pho.to/7891c224_l.png28. http://i.share.pho.to/38135259_o.png29. http://i.share.pho.to/cb289234_o.png30. http://i.share.pho.to/79e115ad_l.png31. http://www.phys4arab.net/vb/showthread.php?t=30682

Image reference links32. http://i.share.pho.to/9e2475b4_o.png33. http://i.cubeupload.com/ERLcXH.png34. To 36) http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/galvan.html37. http://i.cubeupload.com/ERLcXH.png38. http://i.cubeupload.com/7Kmkuj.png39. http://i.cubeupload.com/pMmBAH.png40. http://i.cubeupload.com/Z74xh1.png41. http://cubeupload.com/im/M19NIc.png42. http://cubeupload.com/im/CFIlLm.png43. http://cubeupload.com/im/dk5I7m.png44. http://i.cubeupload.com/xs7kyV.png45. http://carcraftstore.com/images/products/thumb/AM3586.jpg46. http://i.cubeupload.com/2zVJ6H.png47. http://i.cubeupload.com/5pAyyo.png48. http://cubeupload.com/im/UlwSGc.png49. http://i1.olxthailand.com/df/0/ui/post/2014/10/02/8/t/f4c0fe31a19370caec10864f7b35c194.jpeg50. http://static.coleparmer.com/large_images/90000_53.jpg51. http://www.entest.net/product_images/j/372/312FC__10343_thumb.jpg52. http://dicoworldwide.com/picoasi-2.htm53. http://imgur.com/lj2uzNU

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