Sound: Standing Waves and Resonance | Physics in Motion

We visit a university orchestra to help us understand wave interference and how resonance affects waves moving through different types of air columns and strings. We explore how to find various resonant frequencies using the wave velocity equation in combination with an equation that relates the wavelength of a wave to the length of a string, or a closed, or open-ended tube.

[priyeshkumarjha]

So basically when 2 waves of same amplitude and opposite directions meet, we get a standing wave.
These standing waves are what are required for resonance.
Now resonance can be compared to father pushing his child on a swing. Only when the swing has travels to its extreme position can the father push it. If it choses to push it at any other instance of time, the swing may loose its height or in this case amplitude.
Resonance increases amplitude.

In closed wind instruments or string tied to one end, the condition for resonance is that we need a node at closed and antinode at open end. So only 1/4th or 3/4th... waves could be created and thus they have the formula L = n λ /4 where L is length of string/pipe and n is odd

Whereas in In open wind instruments or string tied to both ends, the condition for resonance is that we need 2 nodes at both sides. So only 1/2 or 1 or 1.5 waves could be created and thus they have the formula L = n λ /2 where L is length of string/pipe and n is any no.

[TuroobArab-ohee]

Finally I got the right understanding of these disturbances. They're not hard as I thought 😊

[luisalbertotinajero]

In relation to my previous comment, I should point out that light is focused by means of a lens on the center of a vibrating horizontal string that is fixed at its two ends. The light is made to go through a vertical slot, and with a second lens, it is focused again on a rotating mirror which projects it unto a screen, but it is not clear, how the waveform of the vibrating point is registered, or else, how it is made visible. Professor White says that that if various modes of vibration are active, the resulting compound wave can be observed.

[tbraun]

I'm confused. At 1.22 she says it isn't about how hard you hit it it's about the rhythm in which you hit it. But he doesn't hit it in a certain rhythm, he just hits it once. And then after that she says that through resonance the amplitude can change which means it can get louder or softer, but then in the example the sound it softer when he hits it lighter, and the sound is louder when he hits it harder. So clearly it is about how hard he's hitting it. How is this showing resonance?

[ciompiquartet]

9:44. The cello A string is actually 220 hertz.

[luisalbertotinajero]

Hello.

In Harvey E. White's Modern College Physics, an experiment for visualizing the waveform of a string is described. It involves the use of a rotating mirror. I do not entirely understand the related figure (Fig. 20 E in the 2002 spanish edition). I've looked for videos in YouTube that might show how this experiment is carried out, but not one of those that I've found seems to correspond to the mentioned description. I would very much appreciate any hint you might kindly provide.

[ricksarringhaus]

At 7:24, the chart showing the "String Harmonic Progression" has an error starting with the 5th harmonic. The used 4 in the denominator instead of 5. There is a similar mistake for the 6th harmonic.

[SAINT-ANTONIO]

I wonder how 3D cematic molecular sound, laser or microwave resonance printing could be achieved
to have stuff in 3 to 8 minutes of a molecular gas resin chamber.

Simply thausands of mini laser diodes shaping a 1x1 meter platform.

What it does is actually attract and fuse theese plastic molecules by the electromagnetic wave point
wich has micro focal heating points.
Imagine a 1x1 meter Box.
Each side has directional wave loudspeaker or microwave emitters, so that theese could create a standing wave on 0, 3 inch or so.
Inside the box, wich is a sealed container for gases, a certain blend of molecular plastic structures is sprayed in as a gas.

A computer program calculates and establishes with the omnidirectional emitters of microwave and /or liner loudspeaker module platforms
to ultrasonicly create a focal cavitation point in the gas, causing theese to melt microscopically on the molecular level.
My this theoretically glueing plastic molecules in floating in the air.


Other perhaps better option could be 3D Microwave printing of Plastic gas.
Meaning 6 sides of the inner cube would need to have mininled sized emitters
calibratable in sinus and amplitude able to move a focal point inside a line to create a wave resonance point at any point inside the box.

Could perhaps build a plastic table in 5 minutes after the inner wave chamber was filled with molecular plastic gas

[arctictimberwolf]

Hi Purity Lady, what does it mean when sparks are manifesting around the rim of the bell of My Saxophone?

[SAINT-ANTONIO]

Creating objects by sound.

Sound points fusing plastic or other material gas

[SAINT-ANTONIO]

Example:

Select object
Press GO

Enjoy object like a table, cup or complex tool in 5 minutes out of a device that looks like a microwave, that composed theese objects of gas, waves and heat.