About
Topics
Reflection of light
Description
A light ray from the SOLID YELLOW
object strikes a vertical mirror at point O, and the reflected ray
enters the eye thus allowing the person to see the solid yellow object
inside the mirror shown as dotted lines. By projecting an imaginary
normal line through point O perpendicular to the mirror, known as the
normal, we can measure the angle of incidence, θi and the angle of
reflection, θr. The law of reflection states that θi = θr, or in other
words, the angle of incidence equals the angle of reflection. The dotted
light rays shows the imaginary lines that the image appears to come from
assuming light travels in a straight line path. The arrow head direction
serves to symbolize the direction of light travelling.
Play with
the Reflection Mirror Model to explore the following
- point object with simple ray, to multiple rays entering the eye.
- large object (BLACK) with multiple rays entering the eye
Sample Learning Goals
(a) recall and use the terms for reflection, including normal, angle of
incidence and angle of reflection
(b) state that, for reflection, the
angle of incidence is equal to the angle of reflection and use this
principle
in constructions, measurements and calculations.
Version:
Translations
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Credits
Leong Tze Kwang; lookang
http://iwant2study.org/lookangejss/04waves_13light/ejss_model_mirrorv11/mirrorv11_Simulation.xhtml
Briefing Document: 🔬Reflection JavaScript HTML5 Applet Simulation Model
1. Overview
This document reviews a web page from the "Open Educational Resources / Open Source Physics @ Singapore" website. The primary focus of the page is a JavaScript HTML5 applet simulation model demonstrating the reflection of light. The model, created by Leong Tze Kwang (lookang), is designed to be an interactive educational tool, particularly for secondary-level students learning about optics. The page also contains links to many other interactive physics models.
2. Main Theme: Reflection of Light
The core theme is the exploration and understanding of light reflection using an interactive simulation. The page provides an embedded applet that allows users to manipulate a light ray and a mirror to observe the reflection phenomenon.
3. Key Concepts & Definitions
The webpage explicitly highlights several key concepts:
- Object and Image: The simulation shows a "SOLID YELLOW object" and its reflection (or image) as dotted lines in the mirror. This clarifies how we perceive objects in mirrors.
- Incident Ray and Reflected Ray: The simulation visually demonstrates how a light ray (from the object) strikes the mirror and how that ray is reflected, eventually reaching the observer's eye.
- Normal: The simulation also makes use of an "imaginary normal line through point O perpendicular to the mirror," which is vital to understanding the Law of Reflection.
- Angle of Incidence (θi): The angle between the incident ray and the normal.
- Angle of Reflection (θr): The angle between the reflected ray and the normal.
- Law of Reflection: The page clearly states the law of reflection: "θi = θr, or in other words, the angle of incidence equals the angle of reflection." The simulations is designed to allow students to observe this phenomenon.
4. Simulation Features and Learning Goals
The applet provides interactive elements to explore different scenarios:
- Point Object and Multiple Rays: Users can explore the behavior of a single ray of light or multiple rays entering the eye using a simple, singular object.
- Large Object and Multiple Rays: The model also includes a "large object (BLACK)" so that students can see how the Law of Reflection works with larger, less simple objects.
- Direction of Light: "The arrow head direction serves to symbolize the direction of light travelling."
- Imaginary Lines: The "dotted light rays shows the imaginary lines that the image appears to come from assuming light travels in a straight line path."
- Sample Learning Goals:"(a) recall and use the terms for reflection, including normal, angle of incidence and angle of reflection."
- "(b) state that, for reflection, the angle of incidence is equal to the angle of reflection and use this principle in constructions, measurements and calculations." These learning goals are clearly defined to provide direction to students using the simulation.
5. Accessibility and Technology
- HTML5: The simulation is built using HTML5, making it accessible across various devices, including desktops, laptops, and mobile devices.
- Embeddable: The simulation can be embedded in other webpages using an iframe code. This feature is important for integration into other educational platforms and websites.
- EasyJavaScriptSimulation: The source also shows that the applet was designed using EasyJavaScriptSimulation, which indicates the tools used to develop the interactive model.
6. Broader Context: Open Educational Resources
- Open Source: The page is part of the "Open Educational Resources / Open Source Physics @ Singapore" project, highlighting the commitment to free and accessible educational materials.
- Creative Commons License: The content is licensed under a Creative Commons Attribution-Share Alike 4.0 Singapore License, allowing reuse and adaptation with proper attribution.
- Library of Simulations: This web page is one of a large collection of physics simulations, as shown by the massive list of other applets.
7. Developer and Credits:
- Creator: The simulation was created by Leong Tze Kwang, also known as "lookang".
- Credits: The simulation is hosted at http://iwant2study.org/lookangejss/04waves_13light/ejss_model_mirrorv11/mirrorv11_Simulation.xhtml
8. Key Quotes:
- "The law of reflection states that θi = θr, or in other words, the angle of incidence equals the angle of reflection."
- "The dotted light rays shows the imaginary lines that the image appears to come from assuming light travels in a straight line path."
- "(a) recall and use the terms for reflection, including normal, angle of incidence and angle of reflection"
- "(b) state that, for reflection, the angle of incidence is equal to the angle of reflection and use this principle in constructions, measurements and calculations."
9. Other Notable Points
- The site contains a large number of other physics simulations covering many other areas of the subject (many of which are also interactive and built with EasyJavascriptSimulation). These other simulation models demonstrate the scope of the project.
Conclusion
This simulation provides a valuable, interactive, and easily accessible tool for students to learn about the principles of light reflection. The emphasis on clear definitions, interactive exploration, and well-defined learning goals make it a useful educational resource, especially within the context of open educational resources.
Reflection of Light Study Guide
Quiz
Instructions: Answer the following questions in 2-3 sentences each.
- In the context of reflection, what is the "normal"?
- Describe the angle of incidence in relation to the normal.
- What does the law of reflection state about the angles of incidence and reflection?
- If the angle of incidence is 30 degrees, what is the angle of reflection?
- How does the simulation represent the path of light?
- What does the simulation use to represent the imaginary lines from which the image appears?
- Explain how the simulation illustrates the concept of a point object reflecting light.
- Describe how the simulation depicts a large object reflecting light, and what makes it more complex than a point object?
- What two learning goals are defined by the simulation?
- Besides light reflection, what other topics are covered by simulations from this website?
Answer Key
- The "normal" is an imaginary line drawn perpendicular to the reflecting surface at the point where the incident light ray strikes the surface. It serves as the reference from which the angles of incidence and reflection are measured.
- The angle of incidence is the angle between the incident light ray and the normal line. This angle is crucial in determining how the light will be reflected off of a surface.
- The law of reflection states that the angle of incidence is always equal to the angle of reflection. This is a fundamental principle that governs how light behaves when it bounces off a surface.
- If the angle of incidence is 30 degrees, the angle of reflection will also be 30 degrees, as according to the law of reflection.
- The simulation represents the path of light using arrows, which visually indicate the direction in which the light is travelling. These arrows help users understand the path the light takes from the source to the mirror and to the eye.
- The simulation uses dotted lines to represent the imaginary lines that the image appears to come from. This helps to show how our brains perceive a reflected image as if it were behind the mirror and allows the user to track the imaginary path of the light.
- The simulation illustrates a point object reflecting light by showing a single light ray emanating from the point object, hitting the mirror, and reflecting into the eye. This helps demonstrate the basic principles of light reflection on a small scale.
- The simulation depicts a large object reflecting light by illustrating multiple light rays originating from different points on the object. Each of those rays are reflected according to the law of reflection, making it more complex than a point object where only a single ray is shown.
- The simulation aims to have users recall terms like normal, angle of incidence, and angle of reflection, as well as to state and use the principle that, in reflection, the angle of incidence equals the angle of reflection.
- This website includes a large number of simulations spanning other topics, including kinetic theory of gas, Brownian Motion, oscillators, simple harmonic motion, gravitational fields, projectile motion, friction, magnetism, and many other physics and mathematics concepts.
Essay Questions
Instructions: Answer the following questions in essay format.
- Discuss how the reflection simulation demonstrates the relationship between the incident ray, reflected ray, and the normal line. Explain how the simulation helps clarify the concept of the law of reflection and what would happen if this law was violated.
- Explain how the simulation visually represents the formation of an image due to reflection. Focus on the significance of the dotted lines in the model and describe how these lines help viewers understand the location and appearance of the reflected image.
- Compare and contrast how the simulation depicts the reflection of a point object versus a larger object. What aspects of the law of reflection apply equally to both, and what challenges are presented with the reflection of a larger object?
- Analyze the educational value of interactive simulations like the reflection model described in the source. How do these tools enhance the learning experience compared to traditional methods of teaching about light reflection and its laws?
- Explore the broader context of the website where this reflection simulation is hosted. How do the various simulation models support an integrated approach to learning in different disciplines (e.g., physics, math)? Describe why open-source educational resources are a valuable tool.
Glossary of Key Terms
- Reflection: The bouncing back of light when it strikes a surface.
- Incident Ray: The light ray that strikes a surface before being reflected.
- Reflected Ray: The light ray that bounces off a surface after being reflected.
- Normal: An imaginary line perpendicular to the reflecting surface at the point where the incident ray strikes.
- Angle of Incidence (θi): The angle between the incident ray and the normal.
- Angle of Reflection (θr): The angle between the reflected ray and the normal.
- Law of Reflection: The principle that states the angle of incidence is equal to the angle of reflection (θi = θr).
- Point Object: An object considered to be a single point source of light.
- Open Educational Resources: Freely accessible educational materials that can be used and adapted by anyone.
FAQ: Reflection of Light Simulation
1. What is the main concept explored by the Reflection JavaScript HTML5 Applet Simulation Model?
The simulation primarily focuses on the phenomenon of light reflection, specifically how light rays behave when they encounter a flat, reflective surface like a mirror. It illustrates the basic principles of reflection, including the angles involved.
2. What is the "normal" line, and why is it important in understanding reflection?
The "normal" is an imaginary line drawn perpendicular to the mirror's surface at the point where the incident light ray strikes. It serves as a reference line for measuring the angles of incidence and reflection. Understanding the normal is crucial because the angles are measured relative to it.
3. What are the "angle of incidence" and the "angle of reflection", and how are they related?
The angle of incidence (θi) is the angle between the incoming (incident) light ray and the normal. The angle of reflection (θr) is the angle between the reflected light ray and the normal. The fundamental law of reflection states that the angle of incidence is always equal to the angle of reflection (θi = θr).
4. How does the simulation represent the path of light, including the reflected image?
The simulation uses solid yellow lines to represent real light rays and dotted lines to show the imaginary path of light that forms the image. It demonstrates how the brain interprets reflected light as if it originated from a point behind the mirror, creating the illusion of a virtual image. Arrows are used to show the direction of light travel.
5. What can you explore using the Reflection Mirror Model?
The simulation allows you to explore the reflection of light using: 1) a single point object and multiple rays entering the eye, and 2) a large object with multiple rays entering the eye. This can be used to learn how both small and large objects are perceived in a mirror.
6. What are some of the learning goals associated with this simulation?
The learning goals include being able to recall and correctly use reflection-related terms such as normal, angle of incidence, and angle of reflection. Furthermore, learners should be able to apply the principle that the angle of incidence equals the angle of reflection in different scenarios such as constructions, measurements, and calculations.
7. On what types of devices can this simulation run?
The simulation is designed to run on various platforms, including desktops, laptops (Windows, MacOSX, Linux, Chromebooks), Android/iOS mobile devices, including smartphones and tablets. This cross-platform compatibility makes it widely accessible for learning purposes.
8. Who created this simulation and what other resources are available from the same source?
This simulation was created by Leong Tze Kwang and lookang. This same source, Open Educational Resources / Open Source Physics @ Singapore provides many other interactive simulations, covering a wide array of physics and math topics, ranging from mechanics to electromagnetism and including various games and interactive tools. The site also offers resources for teaching and learning using these simulations.