added centimeter option 
added zoom factor 
updated 20 sept 2016
Available as a Google Play Store App
https://play.google.com/store/apps/details?id=com.ionicframework.vernierapp777926
updated 7 june 2016
Vernier Caliper JavaScript HTML5 Applet Simulation Model by FuKwun Hwang & Loo Kang Wee 
Updated 06 june 2015: EJSS Vernier caliper model
EJSS Vernier caliper model http://weelookang.blogspot.sg/2015/07/ejssverniercalipermodel.html run: Link1 download: Link1 source: Link1: author: FuKwun Hwang, lookang 
31 October 2011 added magnify and random length objects to challenge students to think more, hopefully more fun to figure out for themselves! http://weelookang.blogspot.sg/2010/06/ejsopensourceverniercalipersjava.html https://dl.dropboxusercontent.com/u/44365627/lookangEJSS/export/ejs_model_AAPTVernierCaliper.jar https://dl.dropbox.com/u/44365627/lookangEJSworkspace/export/ejs_AAPTVernierCaliper.jar author: FuKwun and lookang (this remix version) 
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:
 Outside jaws: used to measure external diameter or width of an object (Blue)
 Inside jaws: used to measure internal diameter of an object
 Depth probe: used to measure depths of an object or a hole ( not shown in this model)
 Main scale: gives measurements in mm.
 Vernier gives measurements up to one decimal places in mm
 Retainer: used to block movable part to allow the easy transferring a measurement ( not shown in this model)
The Vernier calipers model has
The method to use a vernier scale or caliper with zero error is to use the formula
 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.
 an object (Green) for external jaws to measure internal diameter of a cylinder for example with slider to control dimensions of the cylinder.
 a slider for zero error slider
 checkbox for hint to scaffold the learners attention and point of focus
 checkbox for answer to show the meaning of reading on the main scale and the vernier scale with zero error calculations if any.
 drop down menu of the various common vernier scales for sense making and additional testing out by learners their ideas of how vernier works.
 fine <> control buttons for learners to manipulate the model with single incremental precision
 slider control for fast changes in the vernier measurement
 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.
Ejs open source Vernier calipers java applet with objects, help & 0error 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 testtube (07Mar2010).
Full screen applet
Java Simulation above is kindly hosted by NTNUJAVA Virtual Physics Laboratory by Professor FuKwun 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
Collaborative Community of EJS (Moderator: lookang) and register , login and download all of them for free :) This work is licensed under a Creative Commons Attribution 3.0 Singapore License
Author: FuKwun and lookang (this remix version)
This work is licensed under a Creative Commons Attribution 2.5 Singapore License
download the simulation here
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) [CCBY3.0 (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
the answer is
=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
answer key:
Q1: the answer is (c). 26.4 mm
Q2: the answer is (a). 16.4 mm
Q3: the answer is (b). 12.6 mm
Added to
http://www.merlot.org/merlot/viewMaterial.htm?id=558989&newcontribution=1
http://www.merlot.org/merlot/viewMaterial.htm?id=558989
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
Ejs open source Vernier calipers java applet with objects, help & 0error 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 testtube (07Mar2010).
Full screen applet
Java Simulation above is kindly hosted by NTNUJAVA Virtual Physics Laboratory by Professor FuKwun 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
Collaborative Community of EJS (Moderator: lookang) and register , login and download all of them for free :) This work is licensed under a Creative Commons Attribution 3.0 Singapore License
Author: FuKwun and lookang (this remix version)
This work is licensed under a Creative Commons Attribution 2.5 Singapore License
download the simulation here
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) [CCBY3.0 (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
the answer is
=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
answer key:
Q1: the answer is (c). 26.4 mm
Q2: the answer is (a). 16.4 mm
Q3: the answer is (b). 12.6 mm
Added to
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 & 0error logic  
