Vernier calipers

Executive Summary:

This briefing document reviews information pertaining to a JavaScript HTML5 applet simulation model of a Vernier caliper, developed by Fu-Kwun Hwang, customized by Loo Kang Wee and Wolfgang Christian using the Easy Java Simulations (EJS) tool. The model, hosted by Open Educational Resources / Open Source Physics @ Singapore, is designed as an interactive tool for learning about measurement, particularly length, using Vernier calipers. It simulates the functionality of a real Vernier caliper, allowing users to practice measuring internal and external dimensions of objects. The model includes various features to aid learning, such as adjustable object dimensions, a zero error slider, hints, answers, and different Vernier scale options. It aligns with learning goals related to accurate measurement using various instruments, including Vernier scales.

Main Themes and Important Ideas/Facts:

• Purpose and Functionality: The primary purpose of the simulation is to provide an interactive and accessible way for learners to understand and practice using a Vernier caliper for measuring length. The model simulates the key functions of a real Vernier caliper, enabling users to measure:
• External dimensions using the lower jaws (Blue object in the model). The description notes these are "used to measure external diameter or width of an object."
• Internal dimensions using the upper jaws (Green object in the model). These are "used to measure internal diameter of an object."
• Depth measurements, although the current model does not visually show the "depth probe" which "is attached to the movable head and slides along the centre of the body."
• Components of a Vernier Caliper (Simulated): The model visually and functionally represents the essential parts of a Vernier caliper:
• Outside jaws (Blue): For external measurements.
• Inside jaws (Green): For internal measurements.
• Main scale: "gives measurements in mm."
• Vernier: "gives measurements up to one decimal places in mm." The model also includes a "drop down menu of the various common vernier scales" to enhance understanding.
• Zero error slider: Allows users to simulate and account for zero errors in measurements.
• Precision of Vernier Calipers: The sources state that "[v]ernier calipers commonly used in industry provide a precision to a hundredth of a millimetre (10 micrometres)." However, the simulation specifically notes that the "Vernier gives measurements up to one decimal places in mm" in its visual elements description, suggesting the default simulation focuses on this level of precision.
• Interactive Learning Features: The model incorporates several features designed to facilitate learning:
• Adjustable objects (Blue and Green) with sliders and drag actions to control their dimensions and position.
• A "checkbox for hint to scaffold the learners attention and point of focus."
• A "checkbox for answer to show the meaning of reading on the main scale and the vernier scale with zero error calculations if any."
• "fine <> control buttons for learners to manipulate the model with single incremental precision."
• A "slider control for fast changes in the vernier measurement."
• A "reset button to bring simulaton back to original (default) setting."
• Educational Alignment: The simulation aligns with learning goals such as the ability to "(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." It can also be used to discuss "errors and uncertainties arise in specific measurements" and the concepts of "precision and accuracy."
• Technical Details and Credits: The model is a "JavaScript HTML5 Applet Simulation Model," making it accessible on various devices including desktops, laptops, tablets, and smartphones. It was "created by Fu-Kwun Hwang, customized by Loo Kang Wee and Wolfgang Christian using the Easy Java Simulations (EJS) version 4.2 authoring and modeling tool." The latest compiled version is noted as being with "EJS 6.02_BETA (201222)."
• Availability and Embeddability: The simulation is hosted online and can be embedded into other webpages using an <iframe> tag provided in the source. Links to various versions and related resources (videos, worksheets, other simulations) are also provided.
• Relation to Micrometers: The text notes that "[a] more precise instrument used for the same purpose is the micrometer," indicating a potential progression in learning about precision measurement. Worksheets related to a micrometer simulation are also mentioned in the "Worksheet" section.
• Developer Notes: Recent updates to the simulation include enhancements for mobile usability (enlarged dragme objects), added "mm" on the top scale, and bug fixes related to depth measurements.

Quotes from Original Sources:

• "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."
• "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)."
• "Outside jaws: used to measure external diameter or width of an object (Blue)"
• "Inside jaws: used to measure internal diameter of an object"
• "Main scale: gives measurements in mm."
• "Vernier gives measurements up to one decimal places in mm"
• "(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."
• "The Vernier calipers model was created by created by Fu-Kwun Hwang, customized by Loo Kang Wee and Wolfgang Christian using the Easy Java Simulations (EJS) version 4.2 authoring and modeling tool."
• "Simulation completed on 4 Nov: ... added 'mm' on top scale ... removed bug for initial tail values (yellow) when measuring depth."

Conclusion:

The Vernier Caliper mm version JavaScript HTML5 Applet Simulation Model is a valuable open educational resource for teaching and learning about length measurement using Vernier calipers. Its interactive features, visual representation of the instrument's components, and alignment with educational goals make it a useful tool for students of various levels. The availability of different versions and related resources further enhances its utility in an educational context. The ongoing development and bug fixes indicate a commitment to maintaining and improving the model.

Frequently Asked Questions: Vernier Calipers Simulation

• What is a vernier caliper and what does this simulation help me understand? A vernier caliper is a precision measuring instrument used to determine internal and external dimensions of objects, and in some cases, depth. This simulation model allows you to interact with a virtual vernier caliper, practicing how to take measurements of different objects. It visually demonstrates the main scale and the vernier scale, helping you understand how their combination provides more precise readings than a standard ruler. You can manipulate objects, adjust the caliper jaws, and read the resulting measurements.
• What are the key parts of a vernier caliper that are represented in the simulation? The simulation visually represents several key components of a vernier caliper, including:
• Outside Jaws (Blue): Used for measuring the external diameter or width of an object.
• Inside Jaws: Used for measuring the internal diameter of an object (Green object in the simulation).
• Main Scale: The fixed scale that provides measurements in millimeters (mm).
• Vernier Scale: The sliding scale that allows for more precise measurements, typically to a fraction of a millimeter (e.g., up to one decimal place in mm in this model).
• Object(s) to Measure: Represented as blue and green shapes with adjustable dimensions and positions. While not explicitly shown in this specific model, some real vernier calipers also have a depth probe and a retainer.
• How can I interact with the simulation to take measurements? The simulation provides several interactive controls:
• You can drag the blue object to position it between the internal jaws.
• Sliders are available to control the width of the blue object for internal measurements and the dimensions of the green cylinder for external measurements.
• You can use a slider or fine control buttons (<>) to manipulate the movable part of the vernier caliper.
• By observing how the vernier scale aligns with the main scale for both the blue and green objects, you can determine the measured dimensions.
• What features are included in the simulation to aid learning? The simulation incorporates several pedagogical features:
• A zero error slider allows you to simulate and understand the impact of zero errors on measurements.
• A checkbox for hints can be enabled to guide your attention to relevant parts of the caliper and the measurement process.
• A checkbox for answers reveals the reading on the main scale and the vernier scale, including any zero error calculations, to help you check your understanding.
• A drop-down menu of various common vernier scales enables you to explore how different scale divisions affect the precision and reading of the caliper.
• Fine control buttons allow for precise adjustments of the vernier scale.
• A reset button returns the simulation to its initial state.
• What types of measurements can I practice with this simulation? This simulation allows you to practice measuring:
• External dimensions: By using the (virtual) outside jaws (interacting with the green object representing a cylinder's internal diameter).
• Internal dimensions: By using the (virtual) inside jaws (interacting with the blue rectangular object representing width). While the model doesn't visually show a depth probe, the principles of reading the vernier scale for depth measurements would be similar.
• What is the intended precision of the vernier caliper simulated here? The description indicates that the vernier scale in this model provides measurements up to one decimal place in millimeters. Real-world vernier calipers commonly used in industry can offer precision to a hundredth of a millimeter (10 micrometers). The simulation also mentions a drop-down menu with various common vernier scales, suggesting different precisions might be selectable for learning purposes.
• How does this simulation relate to learning about errors and uncertainties in measurements? The inclusion of a zero error slider directly addresses the concept of systematic errors in measurement instruments. By manipulating this slider, learners can observe how a misaligned zero point affects all subsequent measurements. The simulation, in conjunction with the "hints" and "answers" features, can help students understand how to properly read a vernier caliper to minimize parallax errors and improve the precision of their measurements, which are key aspects of reducing uncertainties. The provided links to learning outcomes also emphasize the importance of understanding errors, uncertainties, precision, and accuracy in practical work.
• Who created this simulation and what are the underlying tools used? The Vernier Calipers model was created by Fu-Kwun Hwang, with customization by Loo Kang Wee and Wolfgang Christian. It was developed using the Easy Java Simulations (EJS) version 4.2 authoring and modeling tool. The simulation is also available as a JavaScript HTML5 applet, making it accessible on various devices, including computers, laptops, tablets, and smartphones, without the need for additional plugins. The open-source nature of EJS allows for examination and modification of the model for educational purposes.