## Friday, June 11, 2010

### Ejs open source Vernier calipers java applet with objects, help & 0-error logic « on: June 05, 2008, 11:48:46 PM »

 31 October 2011 added magnify and random length objects to challenge students to think more, hopefully more fun to figure out for themselves! https://dl.dropbox.com/u/44365627/lookangEJSworkspace/export/ejs_AAPTVernierCaliper.jar author: Fu-Kwun and lookang (this remix version)
http://youtu.be/zz4Fha5sISo
Learning How to Use the Vernier Caliper Through Open Source Physics Java Simulation

## Vernier Calipers Model

Vernier calipers can measure internal dimensions (using the uppermost jaws in the picture at right), external dimensions using the pictured lower jaws, and depending on the manufacturer, depth measurements by the use of a probe that is attached to the movable head and slides along the centre of the body. This probe is slender and can get into deep grooves that may prove difficult for other measuring tools.
The vernier scales can be in metric measurements on the upper and lower part of the scale.
Vernier calipers commonly used in industry provide a precision to a hundredth of a millimetre (10 micrometres).
A more precise instrument used for the same purpose is the micrometer

## Parts of a vernier caliper:

1. Outside jaws: used to measure external diameter or width of an object (Blue)
2. Inside jaws: used to measure internal diameter of an object
3. Depth probe: used to measure depths of an object or a hole ( not shown in this model)
4. Main scale: gives measurements in mm.
5. Vernier gives measurements up to one decimal places in mm
6. Retainer: used to block movable part to allow the easy transferring a measurement ( not shown in this model)
The Vernier calipers model has
1. an object (Blue) for the internal jaws to measure width of an object with slider to control width of the object and simple drag action to control position of object.
2. an object (Green) for external jaws to measure internal diameter of a cylinder for example with slider to control dimensions of the cylinder.
3. a slider for zero error slider
4. checkbox for hint to scaffold the learners attention and point of focus
5. checkbox for answer to show the meaning of reading on the main scale and the vernier scale with zero error calculations if any.
6. drop down menu of the various common vernier scales for sense making and additional testing out by learners their ideas of how vernier works.
7. fine <> control buttons for learners to manipulate the model with single incremental precision
8. slider control for fast changes in the vernier measurement
9. reset button to bring simulaton back to original (default) setting.

## Zero error

The method to use a vernier scale or caliper with zero error is to use the formula

actual reading = main scale + vernier scale − (zero error)

Zero error may arise due to knocks that cause the calibration at the 0.00 mm when the jaws are perfectly closed or just touching each other.

when the jaws are closed and if the reading is 0.10mm, the zero error is referred to as +0.10mm.The method to use a vernier scale or caliper with zero error is to use the formula 'actual reading = main scale + vernier scale − (zero error)' thus the actual reading is 19.00 + 0.54 − (0.10) = 19.44 mm

Positive zero error refers to the fact that when the jaws of the vernier caliper are just closed, the reading is a positive reading away from the actual reading of 0.00mm. If the reading is 0.10mm, the zero error is referred to as +0.10mm.

when the jaws are closed and if the reading is −0.08mm, the zero error is referred to as −0.08mm..The method to use a vernier scale or caliper with zero error is to use the formula 'actual reading = main scale + vernier scale − (zero error)' thus the actual reading is 19.00 + 0.36 − (−0.08) = 19.44 mm

Negative zero error refers to the fact that when the jaws of the vernier caliper are just closed, the reading is a negative reading away from the actual reading of 0.00mm. If the reading is −0.08mm, the zero error is referred to as −0.08mm.

Micrometer with external measurement

Micrometer with internal measurement

Micrometer with depth measurement

Ejs open source Vernier calipers java applet with objects, help & 0-error logic « on: June 05, 2008, 11:48:46 PM »

Ejs open source Vernier calipers java applet with objects (Sept2009) and zero error logic (Sept2009) with now input field (Nov2009) for checking understanding (29Nov2009) better blue object collision detection, now with depth stem and test-tube (07Mar2010).

Full screen applet
Java Simulation above is kindly hosted by NTNUJAVA Virtual Physics Laboratory by Professor Fu-Kwun Hwang
http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=684.0
alternatively, go direct to http://www.phy.ntnu.edu.tw/ntnujava/index.php?board=28.0
Author: Fu-Kwun and lookang (this remix version)

https://dl.dropbox.com/u/44365627/lookangEJSworkspace/export/ejs_AAPTVernierCaliper.jar
it is no longer embedded :) to make the running on browsers faster

http://commons.wikimedia.org/wiki/File:Vernier_caliper_applet.gif
By Lookang (Own work) [CC-BY-3.0 (www.creativecommons.org/licenses/by/3.0)], via Wikimedia Commons

Q1: What is the reading of the vernier calipers shown below in mm?

or

(a) 20.0
(b) 26.0
(c) 26.4
(d) 30.0
(e) 35.4

try to move the simulation to get this state.

Q2: This vernier caliper has a Zero error = + 0.2 mm What is the correct reading of the vernier calipers shown below in mm?

in cm
or in mm

(a) 16.4
(b) 16.6
(c) 16.8
(d) 22.0
(e) 22.2

=main scale + vernier scale - (zero error)
=16.0 + 0.6 - ( 0.2)
= 16.4 mm

Q3 : The diagram shows a dice being measured using vernier calipers. What is the width of the dice, as recorded by the vernier scale?

(a) 12.0
(b) 12.6
(c) 15.3
(d) 15.6
(e) 18.0

Q1:  the answer is (c). 26.4 mm
Q2: the answer is (a). 16.4 mm
Q3: the answer is (b). 12.6 mm

http://www.merlot.org/merlot/viewMaterial.htm?id=558989&newcontribution=1
http://www.merlot.org/merlot/viewMaterial.htm?id=558989

## Ejs open source Vernier calipers java applet with objects, help & 0-error logic

 Location: Go to Material or Mirror Site Material Type: Simulation Technical Format: Java Applet Date Added to MERLOT: June 20, 2011 Date Modified in MERLOT: June 20, 2011 [Report Broken Link]

 Authors: Fu-Kwun Hwang   National Taiwan Normal University Loo Kang WEE   open source physics
Submitter : lookang wee

Description:
Ejs open source Vernier calipers java applet with objects (Sept2009) and zero error logic (Sept2009) with now input field (Nov2009) for checking understanding (29Nov2009) better blue object collision detection, now with depth stem and test-tube (07Mar2010).

Keywords:
vernier scale, zero error, physics, main scale

Browse in Categories:

Primary Audience: Middle School, High School, College General Ed, College Lower Division, College Upper Division, Graduate School, Professional
Technical Requirements: java runtime

Language: English
Material Version: June 07, 2011
Source Code Available: yes
Section 508 compliant: yes
Cost Involved: no
Creative Commons:

added to Wikimedia and Wikipedia
Direct verniers indicating scale is constructed so that when its zero point is coincident with the start of the data scale, its graduations are at a slightly smaller spacing than those on the data scale and so none but the last graduation coincide with any graduations on the data scale.

Retro verniers indicating scale is constructed so that when its zero point is coincident with the start of the data scale, its graduations are at a slightly bigger spacing than those on the data scale and so none but the last graduation coincide with any graduations on the data scale.

How a vernier scale works

How to use a vernier caliper reading a measurement of 19.44 mm

when the jaws are closed and if the reading is 0.10mm, the zero error is referred to as +0.10mm.The method to use a vernier scale or caliper with zero error is to use the formula 'actual reading = main scale + vernier scale - (zero error)' thus the actual reading is 19.00 + 0.54 - (-0.10) = 19.44 mm

when the jaws are closed and if the reading is -0.08mm, the zero error is referred to as -0.08mm..The method to use a vernier scale or caliper with zero error is to use the formula 'actual reading = main scale + vernier scale - (zero error)' thus the actual reading is 19.00 + 0.36 - (-0.08) = 19.44 mm

ThumbnailDateNameUserSizeDescription
14:11, 27 July 2011Vernier scale zero error +0.10.gif (file)Lookang102 KB
14:11, 27 July 2011Vernier scale zero error -0.08.gif (file)Lookang82 KB

ThumbnailDateNameUserSizeDescription
03:09, 27 July 2011Vernier scale use 0.02 scale measurement is 19.44 mm.gif (file)Lookang103 KB(frame 1)
02:38, 27 July 2011VernierscaleHow a vernier scale works.gif(file)Lookang24 KB
02:22, 27 July 2011Vernier scale Retrograde vernier.gif (file)Lookang25 KB
02:22, 27 July 2011Vernier scale Direct vernier.gif (file)Lookang26 KB

Modifications done are:
1. cant remember now
June 03 2009
34. left and right button for fine control of slider
35. added scaffolds of the hints to be more meaningful, show exactly the difficult cases of understanding the reading with zero errors
36. added the final answer also to display the logic of how the top scale + lower scale + error.
37. fool prove it to work even for difficult cases the scaffolds are dynamically displayed
July 23 2009
38. added autoscale for hard to see scaffolds
39. change the text to the new version in Ejs 4.1 pixel size = true for nicer display
September 08 2009
40. added object blue for internal jaws with proper constraints and push if touch and slider control
41. added green object for external jaws with slider control
42. redesigned the scaffolds for the zero error to reflect correctly the logic of reading with zero error
43. sync the pointers position to correctly reflect the zero error calculation
44. redesign the zero error slider to show 0.05mm instead of e=1 increment to be easily to understand
45. redesign the look and feel of the controls and the color scheme so it is easier to read white top scale on darkgrey top scale and light color bottom scale on black lines.
46. all new objects in Ejs 4.2 instead of the older objects drawing originally
12Sept 2009
47 fix bug due to 0.08 being read as 0.05 instead of 0.1 if the marking are 0, 0.05 0.1. by hwang @ http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=567.30
18Sept 2009
48. added html and png to description
49. added comments to all variables for ease of open source sharing
18Nov2009
50 found a bug created by the pointer vss when l_x = 15.00 mm = 14.00+0.00 mm instead of the correct 15.00+0.00 caused by the slider value not 14.999999999 going to 14 and fixed it by using code
vss = (int)((x/dxm+error*unit+1.e-2)); // introduce to point to include zero error and debug need + 1.e-2 for cases where there may be error is calculation
51 fixed more bug with 2.e-2 for text1 and vss
52 added text input field for learner to test their understanding http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=1309.0 thanks to prof hwang. It has the input field for student checking their understanding especially useful for learning the importance of precision of measurement. This is because 19.40 mm is precise, 19.450 mm is too precise and 19.4 mm is not precise enough for the vernier caliper of smallest unit 0.01 mm.
29Nov2009
53 made it possible to select either external jaws use ( example diameter of green object) or internal jaws (example use on external dimensions of blue rectangle)

54 made the vernier caliper behavior more like a real life one with some boundary detection that works well if lightly pressed like in real life?http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=1313.0
55 it is possible by accident to over-compressed the blue object for teachable moments with the students to illustrate inappropriate use of vernier caliper
56 possible to over force blue object into be vernier caliper like in 3D z direction, but it should work nicely if the movement of the mouse on drag is gentle!
57 used prof hwang's code in blue object on drag and made the blue object behave determistically so 54-55-56 is not going to in future release of the applet, if u r looking for that, download the version 4 at the bottom post.
58 fixed an array out of bound discovered by wolfgang error http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=1183.msg5076;topicseen#msg5076
59 fixed another array runtime error when slider is drag to 70.00mm and beyond
60 made the yellow slider and vernier scale max slide to 69.80 mm to avoid over drag to very large values which is surprising possible, the applet still is measuring.
07March2010
61 added depth stem and object for simulating measurement on objects like test-tube, thanks Prof Hwang inspiration tohttp://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=1408.0 vernier cliper (inch/mm mode, dial mode, measure inner/outer diameter and depth)
13june2010
62 made the dimension of web applet width = 600 to fit http://sgeducation.blogspot.com/2010/06/ejs-open-source-vernier-calipers-java.html
26june2010
63 made the x max view bigger to include part of the depth probe of the vernier caliper
64 made autoscale==true when the depth probe is selected
21 july 2011
added zoom for close up view of the vernier scale on the main scale
27july 2011
fixed bug where 0.02mm is selected the hints is 11.98 mm is shown as 12.00 + .98 mm the top pointer jump ahead due to a code

Code:

if(unit==0.02)out=((int)(v*50+dv))/50.;

the correct code is inserted as

Code:

if(unit==0.02)out=((int)(v*50.+dv))/50.; //// 50. instead of 50 fix bug of pointer

real photo from
http://www.phy.uct.ac.za/courses/c1lab/vfig03a.jpg

Other vernier caliper applets include:
some other applets
http://www.members.shaw.ca/ron.blond/Vern.APPLET/index.html
future work: add the top jaws like above
most populated Vernier calipers applet in the world
http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=52
future work: nil or add object to measure ?
http://people.westminstercollege.edu/faculty/ccline/vernier/vernier.html
this one is Prof Hwang's JDK applet but without the attributions credits to Prof Hwang.
introduced to this by Angeline
http://www.geocities.com/tan.weijie/vernier.html
mine is 4th top hit on google today!
http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=684.0
http://www.stefanelli.eng.br/webpage/en-vernier-caliper-pachymeter-calliper-simulator-millimeter-05-mm.html
Likes: The looks is great
http://www.stefanelli.eng.br/webpage/noindex/en-parts-vernier-caliper.html
Likes: Cool explanation of parts
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