Difference between revisions of "PhET/C2/Bending-Light/English-timed"
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|05:32 | |05:32 | ||
− | | By default slider is on '''Water''' 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. | Drag the slider and place it between '''Water''' and '''Glass''' in the lower medium. | ||
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|05:44 | |05:44 | ||
− | | Now | + | | Now let's measure the intensity of light using '''Intensity''' tool. |
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| 06:00 | | 06:00 | ||
− | | I will place the '''magnifier''' on the incident light. Meter shows 100% intensity. | + | | I will place the '''magnifier''' on the incident light. '''Meter''' shows 100% intensity. |
|- | |- | ||
| 06:08 | | 06:08 | ||
− | | Now drag and place the '''magnifier''' on refracted light. Meter shows value as 86.08%. | + | | Now, drag and place the '''magnifier''' on refracted light. '''Meter''' shows value as 86.08%. |
Intensity decreases because it depends on the medium. | Intensity decreases because it depends on the medium. | ||
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|06:34 | |06:34 | ||
− | | Similarly place the '''magnifier''' on reflected light. '''Meter''' shows value as 13.55%. | + | | Similarly, place the '''magnifier''' on reflected light. '''Meter''' shows value as 13.55%. |
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| 07:00 | | 07:00 | ||
− | |Click on '''Prisms''' screen | + | |Click on '''Prisms''' screen at the bottom of the interface. |
|- | |- | ||
| 07:06 | | 07:06 | ||
− | |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''', | ||
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| 07:22 | | 07:22 | ||
− | | At the bottom of the screen we have- | + | | At the bottom of the screen, we have- |
− | prisms and lenses | + | prisms and lenses, |
|- | |- | ||
| 07:29 | | 07:29 | ||
− | | | + | |slider to change the '''Objects''', |
− | + | check boxes for '''Reflections, Normal''' and '''Protractor'''. | |
'''Reset''' button is at the right hand-side bottom corner. | '''Reset''' button is at the right hand-side bottom corner. | ||
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| 07:52 | | 07:52 | ||
− | |Here arrows indicate direction of motion. '''laser''' can be moved up and down. | + | |Here, arrows indicate direction of motion. '''laser''' can be moved up and down. |
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| 08:03 | | 08:03 | ||
− | |Click on monochromatic beam. Click on the '''laser''' light. | + | |Click on '''monochromatic beam'''. Click on the '''laser''' light. |
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|08:21 | |08:21 | ||
− | | Move the wavelength slider gradually from red to violet. | + | | Move the '''wavelength slider''' gradually from red to violet. |
Notice the bending of light as wavelength changes. | Notice the bending of light as wavelength changes. | ||
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|Drag the screw to change the direction of the prism. | |Drag the screw to change the direction of the prism. | ||
− | As we change the direction notice the bending of light. | + | As we change the direction, notice the bending of light. |
|- | |- | ||
| 08:47 | | 08:47 | ||
− | |As an assignment | + | |As an assignment, change prism to glass slabs and observe the bending of light. |
− | + | ||
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|09:26 | |09:26 | ||
− | | As an assignment | + | | As an assignment: |
Use various lenses and observe the dispersion. | Use various lenses and observe the dispersion. | ||
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| 09:51 | | 09:51 | ||
− | |Tool box at the bottom has two additional tools | + | |Tool box at the bottom has two additional tools '''Speed''' and '''Time'''. |
− | + | ||
− | '''Speed''' and '''Time'''. | + | |
At the bottom we also have '''Angles''' check box. | At the bottom we also have '''Angles''' check box. | ||
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|Now we will change the '''laser''' light to Wave. | |Now we will change the '''laser''' light to Wave. | ||
− | Additionally radio buttons- | + | Additionally radio buttons- '''Normal''' and '''Slow Motion'''. Also, '''Play/Pause''' and '''Forward''' buttons appear. |
− | + | ||
− | '''Normal''' and '''Slow Motion''' Also, '''Play/Pause''' and '''Forward''' buttons appear. | + | |
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| 10:18 | | 10:18 | ||
− | | | + | |Let’s begin the '''simulation'''. |
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|10:23 | |10:23 | ||
− | |Click on red button to turn on the '''laser''' pointer. | + | |Click on red button to turn on the '''laser''' pointer. Let’s use the '''Time''' tool. |
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| Place the '''magnifier''' on the reflected wave. | | Place the '''magnifier''' on the reflected wave. | ||
− | Observe that | + | Observe that the new wave pattern is with reduced amplitude. |
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| Drag and place the '''Speed''' tool on the refracted wave. | | 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 | + | The speed is 0.67 c. Here '''c''' is velocity of light equal to 3x10^8 m/s. Value of speed decreases. |
|- | |- | ||
|11:33 | |11:33 | ||
− | |This is because velocity of light decreases in a material medium. | + | |This is because, velocity of light decreases in a material medium. |
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| 11:48 | | 11:48 | ||
− | | In this tutorial we have learnt | + | | In this tutorial, we have learnt how to use '''Bending Light''', interactive '''PhET simulation'''. |
− | + | ||
− | + | ||
|- | |- | ||
|11:57 | |11:57 | ||
− | | Using this '''simulation''' we have learnt | + | | Using this '''simulation''', we have learnt: |
1. Reflection of light | 1. Reflection of light | ||
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|12:12 | |12:12 | ||
− | |We have also learnt to | + | |We have also learnt to: |
− | + | 1. Use optical instruments like prism and lens | |
|- | |- | ||
|12:19 | |12:19 | ||
− | | | + | |2. Measure intensity of light, measure velocity of light and view different wave patterns. |
|- | |- | ||
|12:29 | |12:29 | ||
− | | The video at the following link summarizes the Spoken Tutorial project. Please download and watch it. | + | | The video at the following link summarizes the '''Spoken Tutorial''' project. Please download and watch it. |
|- | |- | ||
| 12:36 | | 12:36 | ||
− | |The Spoken Tutorial Project team | + | |The '''Spoken Tutorial''' Project team conducts workshops using spoken tutorials and gives certificates on passing online tests. |
|- | |- | ||
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| 12:54 | | 12:54 | ||
− | |This project is partially funded by | + | |This project is partially funded by Pandit Madan Mohan Malaviya National Mission on Teachers and Teaching. |
|- | |- | ||
| 13:03 | | 13:03 | ||
− | | Spoken Tutorial Project is funded by NMEICT, MHRD, Government of India. More information on this mission is available at this link. | + | | Spoken Tutorial Project is funded by '''NMEICT, MHRD,''' Government of India. More information on this mission is available at this link. |
|- | |- | ||
| 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 |
|- | |- | ||
|} | |} |
Latest revision as of 17:41, 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. |
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 let's 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:
1. Use optical instruments like prism and lens |
12:19 | 2. 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 |