Nancyvarkey: 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,..."

2022-08-12T10:10:14Z

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,..."

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{| border = 1
|'''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/ 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 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
|-
|}

PhET-Simulations-for-Physics/C2/Bending-Light/English-timed - Revision history

Nancyvarkey: 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,..."