Difference between revisions of "PhET/C2/Bending-Light/English-timed"

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|-  
 
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|00:07
 
|00:07
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| In this tutorial we will learn,
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| In this tutorial, we will learn how to use''' Bending Light''', interactive '''PhET simulation'''.  
−
 
+
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How to use''' Bending Light''', interactive '''PhET simulation'''.  
+
  
 
|-  
 
|-  
 
|00:14
 
|00:14
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| To follow this tutorial,  
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| To follow this tutorial, learners should be familiar with topics in high school science.  
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+
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Learners should be familiar with topics in high school science.  
+
  
 
|-  
 
|-  
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| Here I am using -  
 
| Here I am using -  
  
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Ubuntu Linux OS Version 14.04  
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'''Ubuntu Linux OS''' version 14.04  
  
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Java version 1.7.0  
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'''Java''' version 1.7.0  
  
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Firefox Web Browser Version 53.02.2.  
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'''Firefox Web Browser''' version 53.02.2.  
  
 
|-  
 
|-  
 
|  00:37
 
|  00:37
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| Using this simulation we will learn,
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| Using this simulation, we will learn:
  
 
1. Reflection of light  
 
1. Reflection of light  
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2. Refraction of light  
 
2. Refraction of light  
  
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3. Dispersion of light.
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3. Dispersion of light  
  
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4. How reflection and refraction varies with different material media.  
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4. How reflection and refraction vary with different material media.  
  
 
|-  
 
|-  
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| We will also learn to,  
 
| We will also learn to,  
  
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5. Use optical instruments like prism and lens
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1. Use optical instruments like prism and lens
  
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6. Measure intensity of light
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2. Measure intensity of light
  
 
|-  
 
|-  
 
|01:02
 
|01:02
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|7. Measure velocity of light and  View different wave patterns.  
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|3. Measure velocity of light and  view different wave patterns.  
  
 
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|-  
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| 01:26
 
| 01:26
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|Refraction, is bending of a light ray, when it enters a medium.  
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|Refraction, is bending of a light ray when it enters a medium.  
  
 
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| 02:09
 
| 02:09
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| To open the simulation, right click on '''bending-light_en.html''' file.  
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| To open the simulation, right-click on '''bending-light_en.html''' file.  
  
 
|-  
 
|-  
 
|02:14
 
|02:14
 
| Select '''Open With Firefox Web Browser''' option.   
 
| Select '''Open With Firefox Web Browser''' option.   
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File opens in the browser.  
 
File opens in the browser.  
  
 
|-  
 
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|02:23
 
|02:23
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|This is the interface for '''Bending Light simulation'''.   
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|This is the '''interface''' for '''Bending Light simulation'''.   
 
|-  
 
|-  
 
|02:28
 
|02:28
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|The interface has three screens,
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|The interface has three screens-''' Intro, Prisms''' and  ''' More Tools'''.
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+
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''' Intro '''
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+
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''' Prisms''' and  ''' More Tools'''.
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| 02:42
 
| 02:42
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| This screen has, '''Ray''' and '''Wave''' radio buttons on the top left corner.
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| This screen has '''Ray''' and '''Wave''' radio buttons on the top left corner,
  
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A movable '''laser'''  pointer to turn on the '''laser'''  light.  
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a movable '''laser'''  pointer to turn on the '''laser'''  light.  
  
 
|-  
 
|-  
 
|02:53
 
|02:53
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| We can see green coloured arrows, when mouse pointer is, placed on the '''laser'''.  
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| We can see green colored arrows when '''mouse pointer''' is placed on the '''laser'''.  
  
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These arrows show the direction, in which the '''laser'''  moves.  
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These arrows show the direction in which the '''laser'''  moves.  
  
 
|-  
 
|-  
 
|03:06
 
|03:06
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| Click and drag the '''laser''', to move it from zero to 90 degrees.   
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| Click and drag the '''laser'''  to move it from zero to 90 degrees.   
  
 
Let us bring the '''laser'''  to its default position.  
 
Let us bring the '''laser'''  to its default position.  
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|Here we see a tool box.   
 
|Here we see a tool box.   
  
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It consists of a, protractor to measure angles, '''Intensity''' tool to measure intensity of light.
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It consists of a protractor to measure angles, '''Intensity''' tool to measure intensity of light.
  
 
|-  
 
|-  
 
|03:32
 
|03:32
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| Below the tool box we have a check box to show '''Normal'''.   
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| 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.  
 
A '''Reset''' button is provided at the right hand side corner, to reset the simulation.  
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| 04:09
 
| 04:09
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| Observe that, as we drag the '''laser'''  pointer, angle of reflection and refraction changes.  
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| Observe that as we drag the '''laser'''  pointer, angle of reflection and refraction changes.  
  
 
|-  
 
|-  
 
| 04:17
 
| 04:17
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|Let’s use the protractor tool to measure angle of, incidence refraction and  reflection.  
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|Let’s use the '''protractor''' tool to measure angle of incidence refraction and  reflection.  
  
 
|-  
 
|-  
 
|04:25
 
|04:25
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| Place the protractor at the intersection point of-
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| Place the protractor at the intersection point of incident ray, normal, refracted and reflected rays.  
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incident ray, normal, refracted and reflected rays.  
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|04:44
 
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| Next we will move on to, right hand side of the '''Intro''' screen.  
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| Next we will move on to right hand side of the '''Intro''' screen.  
  
 
|-  
 
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|04:50
 
|04:50
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| Here, we have controls to measure refractive index in both the media.  
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| Here, we have controls to measure '''refractive index''' in both the media.  
  
 
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| 04:56
 
| 04:56
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|There is a slider to change the material medium.
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|There is a '''slider''' to change the material medium, or buttons to click. Initially, the slider is near '''Air'''.  
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Or buttons to click. Initially, the slider is near '''Air'''.  
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| When medium is changed the angle of refraction changes. '''Index of Refraction(n)''' also changes.  
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| When medium is changed, the angle of refraction changes. '''Index of Refraction(n)''' also changes.  
  
 
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Revision as of 17:05, 10 August 2018

Time Narration
00:01 Welcome to this tutorial on Bending Light, an interactive PhET simulation.
00:07 In this tutorial, we will learn how to use Bending Light, interactive PhET simulation.
00:14 To follow this tutorial, learners should be familiar with topics in high school science.
00:21 Here I am using -

Ubuntu Linux OS version 14.04

Java version 1.7.0

Firefox Web Browser version 53.02.2.

00:37 Using this simulation, we will learn:

1. Reflection of light

2. Refraction of light

3. Dispersion of light

4. How reflection and refraction vary with different material media.

00:52 We will also learn to,

1. Use optical instruments like prism and lens

2. Measure intensity of light

01:02 3. Measure velocity of light and view different wave patterns.
01:08 Let’s define reflection, refraction and dispersion.
01:14 Reflection, is bouncing back of a light ray after hitting any surface.

For example- A mirror reflects the image of the observer.

01:26 Refraction, is bending of a light ray when it enters a medium.
01:32 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.

01:45 Dispersion, is a process of splitting of white light into seven colours.
01:51 For Example, formation of a rainbow on a cloudy day.
01:57 So, let's begin.
01:59 Use the given link to download the simulation.

http://phet.colorado.edu

02:03 I have already downloaded Bending light simulation to my Downloads folder.
02:09 To open the simulation, right-click on bending-light_en.html file.
02:14 Select Open With Firefox Web Browser option.

File opens in the browser.

02:23 This is the interface for Bending Light simulation.
02:28 The interface has three screens- Intro, Prisms and More Tools.
02:35 Let us begin our simulation with Intro screen.

Click on Intro screen to open it.

02:42 This screen has Ray and Wave radio buttons on the top left corner,

a movable laser pointer to turn on the laser light.

02:53 We can see green colored arrows when mouse pointer is placed on the laser.

These arrows show the direction in which the laser moves.

03:06 Click and drag the laser to move it from zero to 90 degrees.

Let us bring the laser to its default position.

03:16 Now let’s move onto the tools at the bottom left.
03:21 Here we see a tool box.

It consists of a protractor to measure angles, Intensity tool to measure intensity of light.

03:32 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.

03:44 Let us begin the simulation.
03:47 We can focus light in the form of a Ray , or a Wave depending on what we choose.
03:54 By default Ray is selected.

To turn on the laser, click the red button on the laser pointer.

04:03 Notice that laser light gets reflected and refracted.
04:09 Observe that as we drag the laser pointer, angle of reflection and refraction changes.
04:17 Let’s use the protractor tool to measure angle of incidence refraction and reflection.
04:25 Place the protractor at the intersection point of incident ray, normal, refracted and reflected rays.
04:35 Observe that angle of incidence is equal to angle of reflection.

Drag the protractor back to its place.

04:44 Next we will move on to right hand side of the Intro screen.
04:50 Here, we have controls to measure refractive index in both the media.
04:56 There is a slider to change the material medium, or buttons to click. Initially, the slider is near Air.
05:07 As we drag the slider, medium changes from Air to Water and then to Glass.
05:15 When medium is changed, the angle of refraction changes. Index of Refraction(n) also changes.
05:24 We can see the changing value in the box. Drag the slider back to Air in the upper medium.
05:32 By default slider is on Water in the lower medium.

Drag the slider and place it between Water and Glass in the lower medium.

05:44 Now lets measure, the intensity of light using Intensity tool.
05:49 Click and drag the Intensity tool to the medium.
05:53 Intensity tool consists of a magnifier and a meter to measure intensity of light.
06:00 I will place the magnifier on the incident light. Meter shows 100% intensity.
06:08 Now drag and place the magnifier on refracted light. Meter shows value as 86.08%.

Intensity decreases because it depends on the medium.

06:24 As we drag the medium slider, value on the intensity meter changes.

This is because angle of refraction changes.

06:34 Similarly place the magnifier on reflected light. Meter shows value as 13.55%.
06:44 You can drag the slider to see a different value of intensity.
06:51 Now, change Ray to Wave and observe the bending of light.
06:56 Now we will move on to Prisms screen.
07:00 Click on Prisms screen, at the bottom of the interface.
07:06 In this screen we have the following tools-

Slider to change the environment,

Monochromatic ray,

07:15 Monochromatic beam, white light, slider to change wavelength of light.
07:22 At the bottom of the screen we have-

prisms and lenses

07:29 Slider to change the Objects.

Check boxes for Reflections, Normal and Protractor.

Reset button is at the right hand-side bottom corner.

07:43 laser has a screw provided at its end. Direction of laser can be changed using this screw.
07:52 Here arrows indicate direction of motion. laser can be moved up and down.
08:00 Now let’s begin the simulation.
08:03 Click on monochromatic beam. Click on the laser light.
08:09 Click on Reflections check box to see multiple reflections.
08:14 Place a prism in the path of light. You can see bending of light.
08:21 Move the wavelength slider gradually from red to violet.

Notice the bending of light as wavelength changes.

08:32 Prism is provided with a screw at its corner.
08:38 Drag the screw to change the direction of the prism.

As we change the direction notice the bending of light.

08:47 As an assignment

Change prism to glass slabs and observe the bending of light.

08:54 Now will see dispersion of light using white light.
08:59 Click on white light tool. Observe the dispersion of light.
09:05 Drag the Objects medium slider and observe the dispersion of light.
09:11 Place a lens in the path of dispersed beam of light.

The dispersed beam of light shows multiple reflections.

09:26 As an assignment

Use various lenses and observe the dispersion.

09:32 Change various Environments and observe the dispersion.
09:37 Now we move on to More Tools screen.
09:41 Click on More Tools screen.

More Tools screen has a combination of tools from Intro and Prisms screens.

09:51 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.

10:04 Now we will change the laser light to Wave.

Additionally radio buttons-

Normal and Slow Motion Also, Play/Pause and Forward buttons appear.

10:18 let’s begin the simulation.
10:21 Turn on the laser light.
10:23 Click on red button to turn on the laser pointer. let’s use the Time tool.
10:31 Drag and place the Time tool in the medium. Time tool has two magnifiers and a Meter.
10:39 Place one of the magnifiers on incident wave and observe the wave pattern.

Now place the other magnifier on the refracted wave.

10:51 Observe the wave pattern. It shows a phase shift.
10:56 Place the magnifier on the reflected wave.

Observe that, the new wave pattern is with reduced amplitude.

11:06 This is because, the reflected wave has much lower intensity.
11:12 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,

11:33 This is because velocity of light decreases in a material medium.
11:39 As an assignment,

Change material medium and notice the change in speed and wave pattern.

11:48 In this tutorial we have learnt,

How to use Bending Light, interactive PhET simulation.

11:57 Using this simulation we have learnt,

1. Reflection of light

2. Refraction of light

3. Dispersion of light

4. How reflection and refraction varies with different material media.

12:12 We have also learnt to,

5. Use optical instruments like prism and lens

12:19 6. Measure intensity of light Measure velocity of light and View different wave patterns.
12:29 The video at the following link summarizes the Spoken Tutorial project. Please download and watch it.
12:36 The Spoken Tutorial Project team, conducts workshops using spoken tutorials and gives certificates on passing online tests.
12:46 For more details, please write to us. Please post your timed queries on this forum.
12:54 This project is partially funded by, Pandit Madan Mohan Malaviya National Mission on Teachers and Teaching.
13:03 Spoken Tutorial Project is funded by NMEICT, MHRD, Government of India. More information on this mission is available at this link.
13:17 This is Madhuri Ganapathi from IIT-Bombay signing off. Thank you for joining

Contributors and Content Editors

Madhurig, PoojaMoolya, Sandhya.np14

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