## Topics

Measurement of length and time

## Description

Play with the Vernier Caliper Model. Test what you've learned by trying the input field.
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
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.

## Sample Learning Goals

(g) describe how to measure a variety of lengths with appropriate accuracy by means of tapes, rules, micrometers and calipers, using a vernier scale as necessary.

## Research

arXiv:1408.3803 [pdf]
Vernier caliper and micrometer computer models using Easy Java Simulation and its pedagogical design feature-ideas to augment learning with real instruments
Loo Kang Wee, Hwee Tiang Ning
Comments: 8 pages, 8 figures, Physics Education journal
Subjects: Physics Education (physics.ed-ph); Instrumentation and Detectors (physics.ins-det)
https://youtu.be/jHoA5M-_1R4

## Video

https://youtu.be/zz4Fha5sISo
https://youtu.be/qXtE07tbK8s

## Version:

1. http://weelookang.blogspot.sg/2015/07/ejss-vernier-caliper-model.html
2. http://weelookang.blogspot.sg/2010/06/ejs-open-source-vernier-calipers-java.html
3. http://iwant2study.org/lookangejss/01_measurement/ejs/ejs_model_AAPTVernierCaliper.jar
4. http://www.opensourcephysics.org/items/detail.cfm?ID=9707
5. http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=684.msg2452#msg2452
6. http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=567.msg2364#msg2364