View source for Apps-On-Physics/C2/Sound-waves/English

{|border=1
|| '''Visual Cue'''
|| '''Narration'''
|-

|| '''Slide Number 1'''

'''Title Slide '''
|| Welcome to the spoken tutorial on '''Sound Waves'''.
|-
|| '''Slide Number 2 '''

'''Learning Objectives'''
|| In this tutorial we will demonstrate,

'''Standing Wave''' and '''Standing Longitudinal Waves Apps'''.

|-
|| '''Slide Number 3'''

'''System Requirements'''
|| Here I am using,

*'''Ubuntu Linux''' OS version 16.04
*Firefox web browser version 62.0.3
|-
|| '''Slide Number 4'''
'''Pre-requitsites''' 

'''https://spoken-tutorial.org'''
|| To follow this tutorial learner should be familiar with '''Apps on Physics'''.

For the pre-requisite tutorials please visit this site.
|-
|| '''Slide Number 5'''

'''Learning Goals'''
|| Using these''' Apps''' we will,
* Demonstrate the formation of a standing wave.
* Explain the formation of '''nodes''' and '''antinodes'''.
* Demonstrate harmonics of a standing wave.

|-
|| '''Slide Number 6'''

'''Learning Goals'''
||Calculate the wavelength and frequency of standing waves.
|-
|| '''Slide Number 7'''

Link for '''Apps on physics'''

'''https://www.walter-fendt.de/html5/phen/'''
|| Use the given link to download the '''Apps'''.

|-
|| Point to the file in the''' Downloads''' folder
|| I have downloaded the '''Apps ''' to my '''Downloads''' folder.
|-
|| Right-click on '''standingwavereflection_en.htm''' file.

Select option '''Open With Firefox Web Browser '''option.
|| Right-click on '''standingwavereflection_en.htm''' file.

Select the option '''Open with Firefox Web Browser'''.

'''Standing Wave App '''opens in the '''browser'''.
|-
|| Point to the radio buttons,

'''Reflection from a fixed end '''and '''Reflection from a free end'''.
|| In the green panel under '''Reflection''' we have two radio buttons.

*'''from a fixed end ''' and 
*'''from a free end'''.
|-
|| Point to '''Reflection from a fixed end.'''
|| By default '''Reflection from a fixed end''' is selected.
|-
|| Point to '''Reset '''and '''Start''' button.
|| Below these radio buttons you can see, '''Reset''' and '''Start '''buttons.
|-
|| Point to '''Start '''>>''' Pause''' >> '''Resume.'''
|| '''Start '''button is a toggle for '''Start, Pause''' and '''Resume'''.
|-
|| Point to the three check-boxes

'''Incidenting wave'''

'''Reflected wave '''and

'''Resultant standing wave'''.
|| At the bottom of the green panel you can see 

*'''Incidenting wave'''
*'''Reflected wave '''and
*'''Resultant standing wave''' check-boxes.
|-
|| Point to the check-boxes.
|| These check-boxes are selected by default.
|-
|| Click '''Start''' button.
|| Click on the '''Start''' button. 
|-
|| Move the cursor to show oscillations on the string.
|| On the yellow panel, observe the propagation of a wave in a string. 


The red wave is the '''Incidenting wave'''.
|-
|| Point the cursor to show the reflection from the fixed end.


Point to the blue '''Reflected wave'''.
|| The blue wave is the '''Reflected wave'''.


Observe that the reflected wave has a phase change of 180 degrees.
|-
|| Point to show the amplitude.
|| Here the incident and reflected waves have the same amplitude.
|-
|| Uncheck the '''Reflected wave'''.
|| Let us uncheck the''' Reflected wave'''.


If we uncheck any of the check-boxes, we cannot see the corresponding wave.
|-
|| Click on the Reflected wave check-box
|| Click the '''Reflected wave''' check-box to make it visible again.
|-
|| Click on the '''Pause''' button.
|| Click on the '''Pause''' button to stop the propagation of the waves.
|-
|| Point to the resultant wave.
|| Here is the resultant '''standing wave'''.
|-
|| Pause the '''App''' when it shows this image.
|| This wave is formed due to the superposition of incident and reflected waves.


The resultant wave is the constructive superposition of the waves.
|-
|| Cursor on the waves.
|| Now I will show the superposition of waves in a step-by-step manner.
|-
|| Click on '''Single step''' radio button.

Point to the animation after clicking.
|| Click on the '''Single steps''' radio button to show the animation step-by-step.
|-
|| Click on the drop down to see the different time period.


Point to '''T/8.'''
|| Here a drop down to show various time periods is seen.


By default it is '''T by 8'''.


We will leave it as it is.
|-
|| Click 3 times on '''Resume''' button.

show Constructive and destructive interference of sound waves.
|| Now click the '''Resume '''button three times to show different superpositions.
|-
|| Click on the Resume button and bring it to Destructive interference.
|| This is destructive interference of sound waves.


Here the waves are out of phase.

So they subtract each other and form a straight line.
|-
|| Click on '''Resume''' button.
|| Click on '''Resume''' button again.
|-
|| Point and show the intermediate superposition.
|| This is an intermediate superposition of waves.


It lies between the constructive and destructive superpositions.
|-
|| Click on '''Resume''' button.
|| Again click on the''' Resume''' button.
|-
|| Point to the wave.
|| This is constructive interference of the waves.

Here the amplitude of the resulting standing wave is, sum of both incident and reflected waves.
|-
|| Continuously click on '''Resume '''button to show the three steps.
|| For the time period '''T by 8''', one '''cycle''' takes three steps to complete. 


'''T by 8''' means 1/8th of the total time period.
|-
|| Select '''T/24 '''from the drop down.

Click on the''' Resume '''button


point to various superpositions.
|| Let us select '''T by 24 ''' from the drop-down.


Click on the ''' Resume '''button continuously to see various superpositions.


Observe that one superposition cycle now takes five steps.
|-
|| Select T/4 and T/12 options >> click Resume button.
|| You can try other options given in the drop-down on your own.
|-
|| Point to''' N '''and '''A.'''
|| After the reflection from the fixed end, you can see '''A '''and '''N''' on the string.
|-
|| Point to '''N '''and '''A'''.
|| Here''' N''' is a''' Node''' and '''A '''is an''' Antinode'''.
|-
|| '''Slide Number 8'''

'''Node and Antinode'''

*'''Node '''is the point where the particles do not have any motion.

*'''Antinode''' is the point where the particle oscillates with maximum amplitude. 
|| Let us define a '''Node''' and an '''Antinode.'''


*'''Node '''is the point where the particles do not have any motion.


*'''Antinode''' is the point where the particle oscillates with maximum amplitude. 
|-
|| '''Slide Number 9'''

'''Assignment'''

Using '''Reflection from free end''' option, show the formation of '''standing waves'''.


Observe the reflection by selecting various time period options.


Explain your observation.
|| As an assignment

Using '''Reflection from free end''' option, show the formation of standing waves.


Observe the reflection by selecting various time period options.


Explain your observation.
|-
||
|| Let us move on to '''Standing longitudinal wave App'''.
|-
|| Right-click on '''standinglongitudinalwaves_en.htm''' file.

Select '''Open with Firefox Web Browser'''.
|| To open the''' App '''right-click on '''standinglongitudinalwaves_en.htm '''file.

Select the option '''Open with Firefox Web Browser'''.
|-
|| Point to the '''App'''.
|| The '''App''' opens in the browser.
|-
|| Highlight the 1<sup>st </sup>line from the paragraph.
|| Here is the information related to the '''App''' interface.
|-
|| Scroll down to see the interface.
|| Scroll down to see the interface completely.
|-
|| Point to the tube.

Point to the blue points.
|| This interface shows a tube filled with air molecules.


The blue dots inside the tube represent the air molecules.
|-
|| Point to both the graphs in given sequence.
|| Here we can see two plots.

'''Displacement of particles''' and '''Divergence from average pressure'''.
|-
|| Point to both the X- axis.

Point to '''Δx'''.

Point to''' Δp'''.
|| X axis represents the length of the tube.


'''Δ(delta)x''' is the change in displacement of molecules from the equilibrium position.


'''Δ(delta)p''' is the '''Divergence from average pressure.'''
|-
|| Point to pink and red waves.
|| Observe the pink and red waves.

They show the instantaneous movement of air molecules.
|-
|| Point to the''' Form of tube''' and move the cursor to show the different radio buttons.
|| In the green panel, under the heading''' Form of tube''', we have three radio buttons.
|-
|| Point to the default selected form.
|| By default '''both sides open''' radio button is selected.
|-
|| Point to the '''Vibrational mode'''.

Point to '''Lower''' and '''Higher '''buttons.
|| Next, under '''Vibrational mode''' we see two buttons, '''Lower '''and '''Higher'''.
|-
|| Point to the '''Lower''' buttons.

Point to show the '''fundamental'''.
|| By default, the '''App '''shows the lowest '''Vibrational mode'''.


The lowest '''vibrational mode''' of the system is known as '''fundamental'''.


'''Fundamental vibrational mode''' is the first harmonic followed by higher harmonics.

|-
|| Point to '''Length of tube '''edit box.
|| We can change the''' Length of the tube''' in this box.
|-
|| Point to '''Length of tube'''.
|| '''Length of the tube''' can be varied between 1''' meter''' to 10''' meters'''.

|-
|| Point to '''Wavelength''' and '''Frequency'''.
|| The''' App ''' calculates the '''Wavelength''' and '''Frequency '''based on the length of the tube.

|-
|| Click on the '''Higher''' button till we get a''' 5<sup>th</sup> overtone'''.
|| Click the '''Higher '''button continuously.

It shows 5 overtones for the six harmonical vibrations.

|-
|| Press '''F5''' key.
|| Press '''F5''' key on the keyboard to reset the '''App'''.

|-
|| Point to the tube.

Move the cursor to show the particles at the middle.

Move the cursor to show the particles at extreme positions.

|| Observe the motion of air molecules.

Molecules in the middle of the tube do not displace from the mean position.

Therefore in the '''Displacement of particles''' graph, '''node''' is in the middle.

|-
|| Show the movement of particles and then point to the graph
|| Observe that particles at the extreme positions are oscillating in and out.

Here particles oscillate with maximum amplitude.

Therefore '''antinode''' is present at the extreme ends of the X- axis.

|-
|| Move the cursor to 2<sup>nd</sup> graph.
|| Let us move to the second graph.

|-
|| Cursor on the interface.
|| Observe the movement of particles inside the tube and graph simultaneously.

|-
|| Point to graph and the tube.
|| In the graph, movement of the pink wave shows the changes in the pressure.

As the particles move towards the center, they get compressed.

so pressure increases.

When they move away pressure decreases.

|-
|| Click on '''one side open Form of tube '''radio button.
|| Under '''Form of tube, '''select '''one side open '''radio button.

|-
|| Cursor on the tube.
|| Observe the movement of particles in this form of the tube.
|-
|| Point to the closed end.
|| Here particles at the closed end are not moving.

Therefore the pressure is maximum at this end.

|-
|| Cursor on the interface.
|| Let us calculate the wavelength in this form of the tube. 

|-
|| Define Wavelength in a text-box.

show the picture for which we have to calculate the wavelength.

|| First let us define wavelength.

Wavelength is the distance between two consecutive peaks.

|-
|| Click on the '''Higher''' button. 

Point to the 1st overtone
|| Click on the '''Higher''' button to show the first overtone.

We have to calculate the wavelength of first overtone wave.

|-
|| '''Slide Number 10'''

'''Wavelength'''


'''L = (n/4)x ''λ'''''

'''''L is length of tube'''''

'''''λ is wavelength'''''

'''''n= 1,2,3,......n'''''


'''''λ=4L/n'''''
|| Mathematically we can write,

'''L = n by 4 of lambda'''


here '''L''' is length of the tube and '''lambda''' is the wavelength.

‘ '''n'''’ can take values from 1 to n.

By rearranging the equation we can write this as 

'''lambda= 4L upon n'''
|-
|| '''Slide Number 11'''

'''Wavelength'''


'''''λ=4L/n'''''


'''''λ=(4 X 1)<nowiki>/3= </nowiki>1.33 m'''''


|| Let us calculate the wavelength.

Observe that the wavelength of the first overtone wave is three-fourth of the complete wave.

Here the value of n is 3.

From the '''App, '''value of length of tube can be taken as '''L'''.

Therefore the calculated value of wavelength is 1.33 '''metre'''.

This is the wavelength of first overtone mode of vibration.
|-
|| '''Slide Number 12'''

'''Frequency'''

The number of complete oscillations per second is known as the frequency of a sound wave. 

It is measured in '''hertz (Hz)'''.

'''f=c/λ'''

'''λ''' is wavelength

'''c''' is speed of sound wave
|| Now we will calculate the frequency of the wave.

The number of complete oscillations per second is the frequency of a sound wave. 


It is measured in '''hertz (Hz)'''.


Frequency is calculated using the formula.

'''f=c/λ'''

'''λ''' is wavelength and 

'''c''' is speed of sound wave
|-
|| Point to the value in the '''App'''.
|| The''' App ''' shows the value of speed of sound wave as 343.5 '''metre per second '''at 20 '''degree Celsius'''.
|-
|| Cursor to show the wave for which frequency has to be calculated.
|| Let us calculate the frequency of the same wave. 
|-
|| Show the picture

'''f=c/λ'''

'''<nowiki>=</nowiki>343.5 / 1.33'''

<nowiki>= </nowiki>258.27 Hz
|| Substitute the values for the above formula from the '''App'''.

The value for the frequency is 258.27 '''Hertz'''.

This value is comparable to the value shown in the '''App'''.
|-
|| '''Slide Number 13'''

'''Tabular Column'''

||Make a tabular column to show the wavelength and frequency for 6 harmonical modes.
|-
|| Click on''' Higher'''.
|| Click on the '''Higher '''button to go to next harmonic.
|-
|| '''Slide Number 14'''

'''Tabular Column '''

Show the tabular column with values
|| Similarly I have calculated frequency and wavelength for higher harmonics.
|-
|| '''Slide Number 15'''

'''Assignment'''

Show the empty table.
|| As an assignment

Change the length of tube to 8 metre.

Calculate the wavelength and frequency for different vibrational modes.
|-
|| '''Slide Number 16'''

'''Assignment'''

Change the '''Form of tube''' to '''both sides closed '''and''' '''explain the graphs.
|| Another assignment.

Change the '''form of tube''' to '''both sides closed '''and explain the graphs.

|-
|| '''Slide Number 17'''

'''Summary'''

|| Let us summarize.

Using these '''Apps''' we have,

* Demonstrated the formation of a standing wave.
* Explained the formation of '''nodes''' and '''antinodes'''.
* Demonstrated harmonics of a standing wave.

|-
|| '''Slide Number 18'''

'''Summary'''

|| Calculated the wavelength and frequency of standing waves.

|-
|| '''Slide Number 19'''

'''Acknowledgement'''

These '''Apps''' were created by '''Walter-fendt''' and his team.
|| These '''Apps '''were created by '''Walter-fendt''' and his team.

|-
|| '''Slide Number 20'''

'''About the Spoken Tutorial project.'''

|| The video at the following link summarizes the Spoken Tutorial project.

Please download and watch it.
|-
|| '''Slide Number 21'''

'''Spoken Tutorial workshops.'''

||The '''Spoken Tutorial Project'''team conducts workshops and gives certificates.

For more details, please write to us.
|-
|| '''Slide Number 22'''

'''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 in this forum.
|-
|| '''Slide Number 23'''

'''Acknowledgement'''
||Spoken Tutorial Project is funded by MHRD, Government of India.

|-
|| 
|| This is Himanshi Karwanje from IIT-Bombay. 

Thank you for joining.
|-
|}