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69
votes
6answers
5k views

Why do tuning forks have two prongs?

I believe the purpose of a tuning fork is to produce a single pure frequency of vibration. How do two coupled vibrating prongs isolate a single frequency? Is it possible to produce the same effect ...
15
votes
1answer
836 views

Why don't tuning forks have three prongs?

I was reading Why tuning forks have two prongs?. The top answer said the reason was to reduce oscillation through the hand holding the other prong. So if having 2 prongs will reduce oscillation loss, ...
13
votes
2answers
507 views

Is the length of the day increasing?

In Frontiers of Astronomy, Fred Hoyle advanced an idea from E.E.R.Holmberg that although the Earth's day was originally much shorter than it is now, and has lengthened owing to tidal friction, that ...
10
votes
3answers
417 views

Resonances in high energy physics

I still do not understand what a resonance precisely is. Is it exactly the same as a particle? Or only an excited state? And why does it make a peak in some diagrams? And which diagrams?
9
votes
1answer
323 views

Why do you only hear high frequencies when a microphone is near its speaker?

The phenomenon I'm talking about is positive feedback, as known from control engineering: when the microphone is too close to its speaker, it can "hear itself", so the signal will be infinitely ...
8
votes
1answer
201 views

Theory behind patterns formed on Chladni plates?

In this video of vibrating Chladni plates we can see small sand particles align themselves into different interesting patterns (also shown in the image below) which correspond to some particular ...
7
votes
3answers
3k views

Does the human body have a resonant fequency? If so, how strong is it?

Inpired by http://music.stackexchange.com/questions/7064/physiological-responses-to-different-rhythms, I'm wondering if the human body has a strong resonant frequency. I guess the fact that that it's ...
6
votes
2answers
900 views

Lots of little questions about radiation of LC circuits

I'm trying to get a more intuitive understanding of resonant inductive coupling. It's supposed be a more efficient way to transfer electrical energy wirelessly, because the coils are only coupled by ...
5
votes
1answer
167 views

Why do we hear this mysterious sound?

Sit in a silent place and then bring your hands close to your ears and cover your ears, you will start hearing some sound but if you remove your hands you don't hear it anymore. Can anyone explain ...
5
votes
2answers
177 views

How can I use sound/resonance to clean sewers?

This probably doesn't fit into the realm of regular questions ; it is more of an applied rather than theory/math question ... Anyway, I'm curious whether a metre diameter speaker fitted over a ...
5
votes
0answers
52 views

To what degree does guitar construction affects the vibration of the strings?

There's an old debate going on in the guitar community about how much does wood choice and body shape affect the sound of an electric guitar. No one denies that there's a difference acoustically (how ...
4
votes
1answer
139 views

Why does a container with fluid make different sounds at different fluid levels?

Have you ever noticed that when you are filling a container with fluid. As it approaches the top, it makes a different sound? You can tell by listening when your about to reach the top. Why is this?
4
votes
1answer
56 views

Is this oscillator driven?

A mass $m$ is attached to a vertical massless spring or a spring constant $k$. Originally, the spring was relaxed because the mass was held by a clip. Suddenly the clip was released. THe mass ...
4
votes
4answers
2k views

How does radio receives signal from particular station?

When you tune your radio (digital or analog) to receive say 100 MHz frequency and while in the environment there are hundreds of channels everywhere around the radio. How does it chooses to receive ...
3
votes
3answers
2k views

Why do we take the first derivative of EPR/ESR spectra?

Apologies if this question is a bit too chemistry-flavoured. In electron paramagnetic resonance spectroscopy, there's a practically ubiquitous convention of plotting the first derivative of the ...
3
votes
1answer
187 views

Free/open source tools for calculating normal modes, failing that, advice

Are there any open source tools for calculating the normal modes of arbitrary objects? Input would be some 3D design format and material properties, output would be movement direction and magnitude ...
3
votes
1answer
158 views

Can soldiers marching at the right frequency realistically cause a bridge to break?

In my physics class it was suggested that ancient armies had a rough understanding of the idea of a resonant frequency and so they "broke step" when crossing bridges so as to avoid a very high $Q$. I ...
3
votes
2answers
300 views

How might a resonant antenna and black body radiation interact?

How does an antenna behave when it is cooled so that its black-body radiation is emitting energy at its resonant frequency? Edit: To clarify, its not how they're related in general, but how might ...
3
votes
1answer
782 views

Static flow of water in the presence of a loudspeaker

The title, I don't know whether it's correct or not, but I came across a video in youtube, http://www.youtube.com/watch?v=_PkgQQqpH2M. The author of video used the title and hence I used the same. ...
3
votes
1answer
1k views

Is it possible to break bulletproof glass with your voice?

In The Adventures of Tintin, an opera singer (the Milanese Nightingale) broke a bulletproof glass case using her voice. Is that scientifically possible? From the Wikipedia page, a typical bulletproof ...
3
votes
1answer
88 views

Electron Spin Resonance and Free electrons

When performing an experiment to observe electron spin resonance, we use DPPH molecules as they contain an unpaired electron on one of the N atoms. My question is, why cant free electrons be used in ...
3
votes
1answer
757 views

How does a stronger magnet affect the MRI image quality?

In which ways is a stronger magnet better for magnetic resonance imaging? I read that: The field strength of the magnet will influence the quality of the MR image regarding chemical shift ...
3
votes
1answer
69 views

Is using a swing an example of normal or of parametric resonance?

Parametric resonance is a situation where the driving frequency is a multiple of the eigenfrequency. Various people say that using a swing and propelling it oneself is such a case, with the driving ...
3
votes
1answer
60 views

Can a room resonate at a frequency lower than the principal frequency?

I'm the bass in our high school a cappella group. Recently we had a performance in our auditorium, and I am almost certain I heard the pitch an octave lower than I was singing. I was singing E3 (164 ...
3
votes
0answers
171 views

Calculation of a Gravity Resonance Keyhole

Can anyone describe the mathematics behind the calculation of a resonance keyhole (for a two-body model)? It seems like the size and position of the keyhole should be a function only of mass and ...
2
votes
2answers
3k views

Phase difference of driving frequency and oscillating frequency

If a mass is attached to a spring and is oscillating (SHM). If a driving force is applied it must be at the same frequency as the mass's oscillation frequency. However I'm told that the phase ...
2
votes
3answers
74 views

Are there any musical instruments which use resonance tubes with two closed ends?

Many musical instruments use resonance tubes with one closed end - all brass instruments (I think), clarinet, etc. There are also instruments where both ends are open (flute, pipes) Are there any ...
2
votes
1answer
583 views

Can sound be used to purify/filter water?

I remember reading about all chicken at a poultry farm being violently sick/dying for apparently no reason. It turned out the culprit was machinery at a nearby factory that emitted sound at a ...
2
votes
2answers
128 views

How does energy transfer between B and E in an EM standing wave?

I'm trying to understand how an electric field induces a magnetic field and vice versa, its associated energy, as well as relating it to my understanding of waves on a string. Using a standing wave ...
2
votes
1answer
564 views

What is the difference between Feshbach resonance and Fano resonance?

What is the interpretation of "resonance" in Feshbach resonance and Fano resonance? What is the difference of Feshbach resonance and Fano resonance?
2
votes
1answer
288 views

Singing: Resonance body open-closed or closed-closed?

Googling yields contradictory results, so here my question: When I sing, my vocal chords vibrate, but my whole body is the resonance body, right? So I would say that when I think about standing waves ...
2
votes
1answer
507 views

Harmonics in an open organ pipe

How to solve the following question? An open organ pipe has two adjacent natural frequencies of 500 and 600 Hz. Assume the speed of sound in the air 340m/s. The length of the organ pipe is? What ...
2
votes
3answers
1k views

Frequency of a Tuning Fork

Question: Which of the following affect the frequency of a tuning fork? Tine stiffness Tine length The force with which it's struck Density of the surrounding air Temperature of the surrounding air ...
2
votes
2answers
82 views

Harmonic Oscillator driven by a Dirac delta-like force

Consider that there is no damping for simplicity. As we know, a driving force of the form $\sin(\omega t)$ will make the oscillator at steady state vibrates at the external frequency $\omega$. What ...
2
votes
1answer
1k views

Does the Breit Wigner formula apply to intermediate virtual particles?

Breit Wigner Formula describes the cross section for interactions that proceed dominantly via a intermediate particle (O*) A+B → O* → C + D: $$σ = \frac{2\Pi}{k^{2}}\frac{Γ_{i}Γ_{f}}{(E-E_{o})^{2} + ...
2
votes
2answers
186 views

Drum head coupled with an RLC circuit

I'm thinking about the possibility of an electroacoustic drum that would be tuned with some kind of RLC circuit. The drum head would have an electromagnet attached to its center, which would be ...
2
votes
1answer
285 views

Complex valued energy

I'm working on a 2D He superfluid system with vortices. I was asked to calculate the kinetic energy of vortex-(anti-)vortex pairs and compare the two situations. One finds in literature that the ...
2
votes
3answers
850 views

How could this person have discovered the resonant frequency from this string of magnets?

I stumbled onto this page http://mylifeisaverage.com/story/1364811/ and the post states that they were all making strings and shapes with these sets of 216 really small spherical earth ...
2
votes
0answers
18 views

Resonance condition in confocal cavity

In a confocal cavity, a beam traverses the length of the resonator 4 times between two transmissions along the same ray. . For example, in the above figure, path difference between two beams that ...
2
votes
0answers
32 views

Math formula for crystal glass resonance [duplicate]

For a music therapy experiment, I have to use several crystal glasses with water and different cylindrical shapes, and make them vibrate and produce different sounds. Is there a math formula that ...
2
votes
0answers
40 views

Reflector Klystron and Isolator for ESR/EPR Experiment

I am doing a lab on ESR/EPR, and I would like to know how the reflector klystron operates. It is very old and the company who made our model does not exist anymore and there are no operation manuals. ...
2
votes
0answers
252 views

Chladni Plate Mathematics

I am a high school student doing an IB Extended Essay investigation concerning the resonant frequencies of Chladni plates of differing materials and sizes. Would someone please explain the definition ...
2
votes
0answers
51 views

Is there an equation that tells you more about the amplitude of an object which is in resonance?

I'm a high school senior and I have to write a paper about resonance and differential equations. I've been searching the Internet for a long time, but I haven't found an equation that is properly ...
2
votes
1answer
138 views

What is the name for the whistling “musical” sounds that change stepwise in pitch when a hollow tube is spun like a lasso?

You have likely heard those sounds, science museums sometimes sell Flexible plastic tubes you can whirl like a lasso. The air rushing by the end of the tube causes these sounds, which are admitted in ...
1
vote
2answers
106 views

An analogy for resonance?

I learned that the phenomena of resonance occurs when the frequency of the applied force is equal to the natural frequency of an object. At this point, an object vibrates with maximum amplitude. How ...
1
vote
1answer
387 views

Resonance Experiment

Today in high school physics class, we performed an experiment on the resonance of sound, with a set up like this... To put it simply, the sound waves are supposed to rebound with the surface of ...
1
vote
1answer
409 views

Resonance and Natural Vibrations in Vacuum

In my Physics textbook, it says that if two pendulums of the same natural frequency are placed next to each other and if one is set into vibration, the other starts resonating and when the first one ...
1
vote
1answer
270 views

Why do we need hard steel balls to produce an unusual ‘chirping’ sound?

When two hard steel balls, or similar, are brought gently into contact with each other, an unusual ‘chirping’ sound may be produced.why do we need this material or shape to produce that sound?
1
vote
2answers
169 views

A foundational question about harmonic motion : 2 pipes with different length and frequencies [closed]

How to solve the following question? A pipe open only at one end has a fundamental frequency of 256Hz. A second pipe, initially identical to the first pipe, is shortened by cutting off a portion ...
1
vote
1answer
33 views

Varying the amplitude of a driven wave

I' d like to know whether varying the amplitude of a system at resonance is possible or not and if it is, how? I've calculated the resonance frequency of a material and I'd like to know the ...