PhET/C2/Bending-Light/English

Visual Cue	Narration
Slide Number 1 Title Slide	Welcome to this tutorial on Bending Light, an interactive PhET simulation.
Slide Number 2 Learning Objectives	In this tutorial we will learn, How to use Bending Light, interactive PhET simulation.
Slide Number 3 Pre-requisites	To follow this tutorial, Learners should be familiar with topics in high school science.
Slide Number 4 System Requirement	Here I am using - Ubuntu Linux OS Version 14.04 Java version 1.7.0 Firefox Web Browser Version 53.02.2.
Slide Number 5 Learning Goals	Using this simulation we will learn, Reflection of light Refraction of light Dispersion of light. How reflection and refraction varies with different material media.
Slide Number 6 Learning Goals	We will also learn to, Use optical instruments like prism and lens Measure intensity of light Measure velocity of light and View different wave patterns.
	Let’s define reflection, refraction and dispersion.
Slide Number 7 Reflection	Reflection is bouncing back of a light ray after hitting any surface. For example- A mirror reflects the image of the observer.
Slide Number 8 Refraction	Refraction is bending of a light ray, when it enters a medium. Light changes its speed and angle of propagation as it enters a different medium. For Example: Bending image of a Pencil in a beaker of water.
Slide Number 9 Dispersion	Dispersion is a process of splitting of white light into seven colours. For Example, Formation of a Rainbow on a cloudy day.
	So, let's begin.
Slide Number 10 Link for PhET simulation http://phet.colorado.edu	Use the given link to download the simulation. http://phet.colorado.edu
Point to the file in Downloads folder.	I have already downloaded Bending light simulation to my Downloads folder.
Right click on bending-light_en.html file. Select Open With Firefox Web Browser option. Point to the browser address.	To open the simulation, right click on bending-light_en.html file. Select Open With Firefox Web Browser option. File opens in the browser.
Cursor on the interface.	This is the interface for Bending Light simulation.
Point to each screen.	The interface has three screens, Intro Prisms and More Tools
Cursor on Intro screen. Click on Intro screen.	Let us begin our simulation with Intro screen. Click on Intro screen to open it.
Cursor on Intro screen. Point to the Ray and Wave radio buttons. Drag and move the laser pointer.	This screen has, Ray and Wave radio buttons on the top left corner. A movable laser pointer to turn on the laser light. We can see green coloured arrows, when mouse pointer is, placed on the laser. These arrows show the direction, in which the laser moves. Click and drag the laser, to move it from zero to 90 degrees. Let us bring the laser to its default position.
Move the cursor to the bottom left.	Now let’s move onto the tools at the bottom left.
Point to the tool box. Point to the protractor tool. Point to Intensity tool. Point to the Reset button.	Here we see a tool box. It consists of a, Protractor to measure angles Intensity tool to measure intensity of light . Below the tool box we have a check box to show Normal. A Reset button is provided at the right hand side corner, to reset the simulation.
Point to the radio buttons Ray and Wave. Point to Ray.	Let us begin the simulation. We can focus light in the form of a Ray , or a Wave depending on what we choose. By default Ray is selected. To turn on the laser, click the red button on the laser pointer.
Point to the reflected and refracted ray.	Notice that laser light gets reflected and refracted.
Click and drag the laser .	Observe that, as we drag the laser pointer, angle of reflection and refraction changes.
Place the protractor on the normal. Measure the angles.	Let’s use the protractor tool to measure angle of, incidence refraction and reflection. Place the protractor at the intersection point of- incident ray, normal, refracted and reflected rays. Observe that angle of incidence is equal to angle of reflection. Drag the protractor back to its place.
Move the cursor to right hand-side of the screen. Point to the controls- to measure refractive index.	Next we will move on to, right hand side of the Intro screen. Here, we have controls to measure refractive index in both the media.
Point to the slider. Move the cursor to slider. Drag the slider. Point to index of Refraction. Point to the value. Drag the slider to Water	There is a slider to change the material medium. Or buttons to click. Initially, the slider is near Air. As we drag the slider, medium changes from Air to Water and then to Glass. When medium is changed the angle of refraction changes. Index of Refraction(n) also changes. We can see the changing value in the box. Drag the slider back to Air in the upper medium. By default slider is on Water in the lower medium. Drag the slider and place it between Water and Glass in the lower medium.
Point to intensity tool.	Now lets measure, the intensity of light using Intensity tool.
Click on Intensity tool. Point to the magnifier and meter.	Click and drag the Intensity tool to the medium. Intensity tool consists of a magnifier and a meter to measure intensity of light.
Drag and place. Point to meter.	I will place the magnifier on the incident light. Meter shows 100% intensity.
Drag and place. Point to the meter. Drag the slider.	Now drag and place the magnifier on refracted light. Meter shows value as 86.08%. Intensity decreases because it depends on the medium. As we drag the medium slider, value on the intensity meter changes. This is because angle of refraction changes.
Place the magnifier on reflected light. Point to the meter.	Similarly place the magnifier on reflected light. Meter shows value as 13.55%. You can drag the slider to see a different value of intensity.
Point to the wave radio button. Point to the bending.	Now, change Ray to Wave and observe the bending of light.
Click on Prisms screen.	Now we will move on to Prisms screen. Click on Prisms screen, at the bottom of the interface.
Point various tools on the screen.	In this screen we have the following tools- Slider to change the environment Monochromatic ray Monochromatic beam White light Slider to change wavelength of light.
Move the cursor to the bottom of the screen. Point to prisms, Point to medium slider, Point to Check boxes, Point to Protractor. Point to Reset button.	At the bottom of the screen we have- Prisms and lenses Slider to change the Objects. Check boxes for Reflections, Normal and Protractor. Reset button is at the right hand-side bottom corner.
Point to the screw. Change the direction using the screw.	laser has a screw provided at its end. Direction of laser can be changed using this screw. Here arrows indicate direction of motion. laser can also can be moved up and down.
Click laser light. Click on Reflections check box	Now let’s begin the simulation. Click on Monochromatic beam. Click on the laser light. Click on Reflections check box to see multiple reflections.
Place the prism on the path. Point the cursor to the path of light.	Place a Prism in the path of light. You can see bending of light.
Move the wavelength slider gradually. Point to the bending of light.	Move the wavelength slider gradually from red to violet. Notice the bending of light as wavelength changes.
Point to the screw. Drag the screw to change direction. Notice the bending.	Prism is provided with a screw at its corner. Drag the screw to change the direction of the prism. As we change the direction notice the bending of light.
Slide Number 11 Assignment	As an assignment Change prism to glass slabs and observe the bending of light.
Cursor on the screen.	Now will see dispersion of light using white light.
Click on White light tool. Point to the dispersion.	Click on White light tool. Observe the dispersion of light.
Drag the slider and observer.	Drag the Objects medium slider and observe the dispersion of light.
Place the lens in the path of the beam. Point to multiple reflections.	Place a lens in the path of dispersed beam of light. The dispersed beam of light shows multiple reflections.
Slide Number 12 Assignment	As an assignment Use various lenses and observe the dispersion. Change various Environments and observe the dispersion.
Cursor on the screen.	Now we move on to More Tools screen.
Click on More Tools screen. Point to all the tools on the screen.	Click on More Tools screen. More Tools screen has a combination of tools from Intro and Prisms screens.
Point to Speed and Time tool. Point to Angles tool.	Tool box at the bottom has two additional tools: Speed and Time. At the bottom we also have Angles check box. Click on the Angles check box.
Click on Wave radio. Normal and Slow Motion Play/Pause Forward	Now we will change the laser light to Wave. Additionally radio buttons- Normal and Slow Motion Also, Play/Pause and Forward buttons appear.
	let’s begin the simulation
Click on Time tool	Turn on the laser light. Click on red button to turn on the laser pointer. let’s use the Time tool. Drag and place the Time tool in the medium. Time tool has two magnifiers and a Meter.
Drag an place the Time tool. Place the magnifiers on Incident and refracted waves.	Place one of the magnifiers on incident wave and observe the wave pattern. Now place the other magnifier on the refracted wave. Observe the wave pattern. It shows a phase shift.
Place the magnifier on reflected ray. Point to the reduced amplitude.	Place the magnifier on the reflected wave. Observe that, the new wave pattern is with reduced amplitude. This is because, the reflected wave has much lower intensity.
Drag and place on the refracted wave. Point to the speed.	Drag and place the Speed tool on the refracted wave. The speed is 0.67 c. Here c is velocity of light equal to 3x10^8 m/s. Value of speed decreases, This is because velocity of light decreases in a material medium.
Slide Number 13 Assignment	As an assignment, Change material medium and notice the change in speed and wave pattern.
	Let’s summarize.
Slide Number 14 Summary	In this tutorial we have learnt, How to use Bending Light, interactive PhET simulation.
Slide Number 15 Summary	Using this simulation we have learnt, Reflection of light Refraction of light Dispersion of light How reflection and refraction varies with different material media.
Slide Number 16 Summary	We have also learnt to, Use optical instruments like prism and lens Measure intensity of light Measure velocity of light and View different wave patterns.
Slide Number 17 About Spoken Tutorial project	The video at the following link summarizes the Spoken Tutorial project. Please download and watch it.
Slide Number 18 Spoken Tutorial workshops	The Spoken Tutorial Project team, conducts workshops using spoken tutorials and gives certificates on passing online tests. For more details, please write to us.
Slide Number 19 Forum for specific questions: Do you have questions in THIS Spoken Tutorial? Please visit this site Choose the minute and second where you have the question. Explain your question briefly Someone from our team will answer them.	Please post your timed queries on this forum.
Slide Number 20 Acknowledgements	This project is partially funded by, Pandit Madan Mohan Malaviya National Mission on Teachers and Teaching.
Slide Number 21 Acknowledgement	Spoken Tutorial Project is funded by NMEICT, MHRD, Government of India. More information on this mission is available at this link.
	This is Madhuri Ganapathi from IIT-Bombay signing off. Thank you for joining

Contributors and Content Editors

Madhurig, Snehalathak