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

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(Created page with "{| border = 1 |'''Time''' |'''Narration''' |- |00:01 |Welcome to this tutorial on '''Bending Light''', an interactive PhET simulation. |- |00:07 | In this tutorial we wil...")
 
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|-  
 
|-  
 
|00:01
 
|00:01
−
|Welcome to this tutorial on '''Bending Light''', an interactive PhET simulation.  
+
|Welcome to this tutorial on '''Bending Light''', an interactive '''PhET simulation'''.  
  
 
|-  
 
|-  
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| In this tutorial we will learn,  
 
| In this tutorial we will learn,  
  
−
How to use''' Bending Light, '''interactive PhET simulation.  
+
How to use''' Bending Light, interactive '''PhET simulation'''.  
  
 
|-  
 
|-  
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| Using this simulation we will learn,  
 
| Using this simulation we will learn,  
  
−
Reflection of light  
+
1. Reflection of light  
  
−
Refraction of light  
+
2. Refraction of light  
  
−
Dispersion of light.  
+
3. Dispersion of light.  
  
−
How reflection and refraction varies with different material media.  
+
4. How reflection and refraction varies with different material media.  
  
 
|-  
 
|-  
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| We will also learn to,  
 
| We will also learn to,  
  
−
Use optical instruments like prism and lens
+
5. Use optical instruments like prism and lens
  
−
Measure intensity of light
+
6. Measure intensity of light
  
 
|-  
 
|-  
 
|01:02
 
|01:02
−
| Measure velocity of light and  View different wave patterns.  
+
|7. Measure velocity of light and  View different wave patterns.  
  
 
|-  
 
|-  
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|-  
 
|-  
 
| 01:14
 
| 01:14
−
| '''Reflection''' is bouncing back of a light ray after hitting any surface.  
+
| Reflection, is bouncing back of a light ray after hitting any surface.  
  
 
For example- A mirror reflects the image of the observer.  
 
For example- A mirror reflects the image of the observer.  
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|-  
 
|-  
 
| 01:26
 
| 01:26
−
|'''Refraction''' is bending of a light ray, when it enters a medium.  
+
|Refraction, is bending of a light ray, when it enters a medium.  
  
 
|-  
 
|-  
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| Light changes its speed and angle of propagation as it enters a different 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.  
+
For Example: Bending image of a pencil in a beaker of water.  
  
 
|-  
 
|-  
 
| 01:45
 
| 01:45
−
|'''Dispersion ''' is a process of splitting of white light into seven colours.  
+
|Dispersion, is a process of splitting of white light into seven colours.  
  
 
|-  
 
|-  
 
|01:51
 
|01:51
−
| For Example, Formation of a Rainbow on a cloudy day.  
+
| For Example, formation of a rainbow on a cloudy day.  
  
 
|-  
 
|-  
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|-  
 
|-  
 
| 02:03
 
| 02:03
−
|I have already downloaded '''Bending light''' simulation to my '''Downloads''' folder.  
+
|I have already downloaded '''Bending light simulation''' to my '''Downloads''' folder.  
  
 
|-  
 
|-  
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|-  
 
|-  
 
|02:14
 
|02:14
−
| Select '''Open With Firefox Web Browser''' option.  File opens in the browser.  
+
| Select '''Open With Firefox Web Browser''' option.   
 +
 
 +
File opens in the browser.  
  
 
|-  
 
|-  
 
|02:23
 
|02:23
−
|This is the interface for '''Bending Light''' simulation.  
+
|This is the interface for '''Bending Light simulation'''.
 
|-  
 
|-  
 
|02:28
 
|02:28
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''' Intro '''
 
''' Intro '''
  
−
''' Prisms''' and  ''' More Tools '''
+
''' Prisms''' and  ''' More Tools'''.
  
 
|-  
 
|-  
 
|02:35
 
|02:35
−
|Let us begin our simulation with '''Intro''' screen. Click on '''Intro''' screen to open it.  
+
|Let us begin our simulation with '''Intro''' screen.  
 +
 
 +
Click on '''Intro''' screen to open it.  
  
 
|-  
 
|-  
 
| 02:42
 
| 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.  
+
| 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
 
|02:53
−
| We can see green coloured arrows, when mouse pointer is, placed on the '''laser'''. These arrows show the direction, in which the '''laser'''  moves.  
+
| We can see green coloured arrows, when mouse pointer is, placed on the '''laser'''.  
 +
 
 +
These arrows show the direction, in which the '''laser'''  moves.  
  
 
|-  
 
|-  
 
|03:06
 
|03:06
−
| Click and drag the '''laser''',  to move it from zero to 90 degrees.  Let us bring the '''laser'''  to its default position.  
+
| Click and drag the '''laser''',  to move it from zero to 90 degrees.   
 +
 
 +
Let us bring the '''laser'''  to its default position.  
  
 
|-  
 
|-  
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|-  
 
|-  
 
| 03:21
 
| 03:21
−
|Here we see a tool box.  It consists of a, '''Protractor''' to measure angles '''Intensity''' tool to measure intensity of light.
+
|Here we see a tool box.   
 +
 
 +
It consists of a, Protractor to measure angles, '''Intensity''' tool to measure intensity of light.
  
 
|-  
 
|-  
 
|03:32
 
|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.  
+
| 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
 
| 03:44
−
| Let us begin the simulation.  
+
| Let us begin the '''simulation'''.  
  
 
|-  
 
|-  
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|-  
 
|-  
 
|03:54
 
|03:54
−
| By default '''Ray''' is selected.  To turn on the '''laser''', click the red button on the '''laser'''  pointer.  
+
| By default '''Ray''' is selected.   
 +
 
 +
To turn on the '''laser''', click the red button on the '''laser'''  pointer.  
  
 
|-  
 
|-  
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|-  
 
|-  
 
| 04:17
 
| 04:17
−
|Let’s use the '''protractor''' tool to measure angle of, incidence refraction and  reflection.  
+
|Let’s use the protractor tool to measure angle of, incidence refraction and  reflection.  
  
 
|-  
 
|-  
 
|04:25
 
|04:25
−
| Place the '''protractor''' at the intersection point of-  
+
| Place the protractor at the intersection point of-  
  
 
incident ray, normal, refracted and reflected rays.  
 
incident ray, normal, refracted and reflected rays.  
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|-  
 
|-  
 
|04:35
 
|04:35
−
| Observe that angle of incidence is equal to angle of reflection. Drag the '''protractor''' back to its place.  
+
| Observe that angle of incidence is equal to angle of reflection.  
 +
 
 +
Drag the protractor back to its place.  
  
 
|-  
 
|-  
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|-  
 
|-  
 
|04:50
 
|04:50
−
| Here, we have controls to measure '''refractive index''' in both the media.  
+
| Here, we have controls to measure refractive index in both the media.  
  
 
|-  
 
|-  
 
| 04:56
 
| 04:56
−
|There is a slider to change the material medium. Or buttons to click. Initially, the slider is near '''Air'''.  
+
|There is a slider to change the material medium.  
 +
Or buttons to click. Initially, the slider is near '''Air'''.  
  
 
|-  
 
|-  
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|-  
 
|-  
 
|05:32
 
|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.  
+
| 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
 
|05:44
−
|  Now lets measure, the '''intensity''' of light using '''Intensity''' tool.  
+
|  Now lets measure, the intensity of light using '''Intensity''' tool.  
  
 
|-  
 
|-  
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|-  
 
|-  
 
| 06:08
 
| 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.  
+
| 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
 
|06:24
−
| As we drag the medium slider, value on the intensity meter changes. This is because angle of refraction changes.  
+
| As we drag the medium slider, value on the intensity meter changes.  
 +
 
 +
This is because angle of refraction changes.  
  
 
|-  
 
|-  
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|-  
 
|-  
 
| 06:51
 
| 06:51
−
| Now, change '''Ray''' to '''Wave''' and observe the '''bending of light'''.  
+
| Now, change '''Ray''' to '''Wave''' and observe the bending of light.  
  
 
|-  
 
|-  
 
|  06:56
 
|  06:56
−
|Now we will move on to Prisms screen.  
+
|Now we will move on to '''Prisms''' screen.  
  
 
|-  
 
|-  
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|In this screen we have the following tools-  
 
|In this screen we have the following tools-  
  
−
Slider to change the '''environment'''
+
Slider to change the '''environment''',
  
−
'''Monochromatic ray'''
+
Monochromatic ray,
  
 
|-  
 
|-  
 
|07:15
 
|07:15
−
| '''Monochromatic beam'''  '''White light''' Slider to change '''wavelength''' of light.  
+
| Monochromatic beam, white light, slider to change wavelength of light.  
  
 
|-  
 
|-  
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| At the bottom of the screen we have-  
 
| At the bottom of the screen we have-  
  
−
''' Prisms''' and '''lenses'''
+
prisms and lenses
  
 
|-  
 
|-  
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|-  
 
|-  
 
| 08:00
 
| 08:00
−
|Now let’s begin the simulation.  
+
|Now let’s begin the '''simulation'''.  
 
   
 
   
 
|-  
 
|-  
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|-  
 
|-  
 
| 08:14
 
| 08:14
−
| Place a '''Prism''' in the path of light. You can see bending of light.  
+
| Place a prism in the path of light. You can see bending of light.  
  
 
|-  
 
|-  
 
|08:21
 
|08:21
−
| Move the '''wavelength''' slider gradually from red to violet.  Notice the bending of light as '''wavelength''' changes.  
+
| Move the wavelength slider gradually from red to violet.  Notice the bending of light as wavelength changes.  
  
 
|-  
 
|-  
 
| 08:32
 
| 08:32
−
|'''Prism''' is provided with a screw at its corner.  
+
|Prism is provided with a screw at its corner.  
  
 
|-  
 
|-  
 
| 08:38
 
| 08:38
−
|Drag the screw to change the direction of the '''prism'''. As we change the direction notice the bending of light.  
+
|Drag the screw to change the direction of the prism.
 +
 
 +
As we change the direction notice the bending of light.  
  
 
|-  
 
|-  
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|-  
 
|-  
 
|08:59
 
|08:59
−
| Click on '''White light''' tool. Observe the dispersion of light.  
+
| Click on '''white light''' tool. Observe the dispersion of light.  
  
 
|-  
 
|-  
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|-  
 
|-  
 
|  09:11
 
|  09:11
−
|Place a lens in the path of dispersed beam of light. The dispersed beam of light shows multiple reflections.  
+
|Place a lens in the path of dispersed beam of light.  
 +
 
 +
The dispersed beam of light shows multiple reflections.  
  
 
|-  
 
|-  
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|-  
 
|-  
 
| 09:37
 
| 09:37
−
|Now we move on to More Tools screen.  
+
|Now we move on to '''More Tools''' screen.  
  
 
|-  
 
|-  
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|Tool box at the bottom has two additional tools:  
 
|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.  
+
'''Speed''' and '''Time'''.
 +
 
 +
At the bottom we also have '''Angles''' check box. Click on the '''Angles''' check box.  
  
 
|-  
 
|-  
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|-  
 
|-  
 
|  10:18
 
|  10:18
−
|let’s begin the simulation  
+
|let’s begin the '''simulation'''.
  
 
|-  
 
|-  
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|-  
 
|-  
 
|10:39
 
|10:39
−
| Place one of the '''magnifiers''' on incident wave and observe the wave pattern. Now place the other '''magnifier''' on the refracted wave.  
+
| Place one of the '''magnifiers''' on incident wave and observe the wave pattern.  
 +
 
 +
Now place the other '''magnifier''' on the refracted wave.  
  
 
|-  
 
|-  
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|-  
 
|-  
 
|10:56
 
|10:56
−
| Place the '''magnifier''' on the reflected wave. Observe that, the new wave pattern is with reduced '''amplitude'''.  
+
| Place the '''magnifier''' on the reflected wave.  
 +
 
 +
Observe that, the new wave pattern is with reduced amplitude.  
  
 
|-  
 
|-  
 
|11:06
 
|11:06
−
|This is because, the reflected wave has much lower '''intensity'''.  
+
|This is because, the reflected wave has much lower intensity.  
  
 
|-  
 
|-  
 
|11:12
 
|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,  
+
| 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,  
  
 
|-  
 
|-  
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| In this tutorial we have learnt,  
 
| In this tutorial we have learnt,  
  
−
How to use '''Bending Light''', interactive PhET simulation.  
+
How to use '''Bending Light''', interactive '''PhET simulation'''.  
  
 
|-  
 
|-  
 
|11:57
 
|11:57
−
| Using this simulation we have learnt,  
+
| Using this '''simulation''' we have learnt,  
  
−
Reflection of light  
+
1. Reflection of light  
  
−
Refraction of light  
+
2. Refraction of light  
  
−
Dispersion of light  
+
3. Dispersion of light  
  
−
How reflection and refraction varies with different material media.
+
4. How reflection and refraction varies with different material media.
  
 
|-  
 
|-  
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|We have also learnt to,  
 
|We have also learnt to,  
  
−
Use optical instruments like prism and lens  
+
5. Use optical instruments like prism and lens  
  
 
|-  
 
|-  
 
|12:19
 
|12:19
−
|Measure intensity of light Measure velocity of light and View different wave patterns.  
+
|6. Measure intensity of light Measure velocity of light and View different wave patterns.  
  
 
|-  
 
|-  
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|-  
 
|-  
 
| 12:36
 
| 12:36
−
|The '''Spoken Tutorial Project '''team,conducts workshops using spoken tutorials and gives certificates on passing online tests.
+
|The Spoken Tutorial Project team, conducts workshops using spoken tutorials and gives certificates on passing online tests.
 
   
 
   
 
|-
 
|-
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|  13:17
 
|  13:17
 
| This is Madhuri Ganapathi from IIT-Bombay signing off. Thank you for joining  
 
| This is Madhuri Ganapathi from IIT-Bombay signing off. Thank you for joining  
−
 
+
|-
 
|}
 
|}

Revision as of 18:44, 7 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 varies with different material media.

00:52 We will also learn to,

5. Use optical instruments like prism and lens

6. Measure intensity of light

01:02 7. 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 coloured 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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