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Questions tagged [resonance]

Resonance is a characteristic of physical systems having a structure that allows energy to flow between various states at a specific, oscillatory rate (resonant frequency). For a stable resonant system at steady state the internal energy is either fixed without losses or the rate of energy input is equal to the energy losses.

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Resonant frequencies in air filled closed cylinder

I want to calculate the resonant frequencies of a closed cylinder covered with rigid walls. The cylinder is of dimensions: diameter = $1m$, length = $1m$. Would this fundamental mode formula be ...
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How is “linewidth” defined for a damped driven oscillator?

Suppose we have a damped driven harmonic oscillator governed by the following equation of motion: $$\ddot \phi(t) + 2 \beta \dot \phi(t) + \omega_0^2 \phi(t) = J(t) \, .$$ In the case that $J(t) = A \...
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Is there a way to calculate the $Q$-factor?

I’d like to calculate the $Q$-factor for an acoustically resonating object. I’d like to keep the tests to a minimal, none if possible. Is there any way to do this?
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Vibrating string as a dynamic system

It's known first order dynamical systems had one energy storage (example C, in RC circuits) these systems act as a filter but don't resonate, on the other hand a second order system had two energy-...
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Loudspeaker attached to cylinder - effect on speaker SPL?

I have a loudspeaker that is facing into a long cylindrical piece of PVC pipe of length $L$. The loudspeaker is sealed in so that no air can escape around the edges. The pipe is open at the other end. ...
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Loudspeaker attached to cylinder - closed or open?

I have a loudspeaker that is facing into a long cylindrical piece of PVC pipe of length L. The loudspeaker is sealed in so that no air can escape around the edges. The pipe is open at the other end. ...
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Why will a guitar string “ring” when I resonate my vocal chords at the same pitch as the string?

From a resting state, a guitar string will begin to ring as I resonate my vocal chords. If I make a fairly loud, and high-frequency "oo" sound at 440hz, then the A string on my guitar begins to ...
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SOUND WAVES :: organ pipes [duplicate]

Why doesn't sound wave escape in a open end pipe, why does it reflect again at open end of organ pipe when it can just move outside.
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Acoustics - tiny ultralow impedance speaker? [closed]

Here's a theoretical question that hopefully someone will be able to shed some light on. Apologies if this is the wrong forum, I figured the electrical engineering community would be more into ...
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36 views

Chladni Patterns (Length Factor)

I've recently been conducting experiments on the Chladni Plates, testing out how the length of a square Chladni plate (and consequently its area) affects the frequency at which each respective chladni ...
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23 views

Resonant frequencies of a fully closed tube

What is the pattern for resonant frequencies of a tube closed at BOTH ends? The cases for the string, the open tube and the tube closed at one ends are well known.
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How does a guitar work?

Here are four different possible ways: The plucked string vibrates longitudinally, vibrating the air around it. This vibrating air then causes the air inside the sound box to vibrate also, which ...
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How to understand complex masses of unstable particles? The conceptual problem of calculating decay rate

If a particle has a complex mass, $p^2-m^2=0$ leads to $p^μ \notin \mathbb R^4$. What does it mean? When you want to calculate S-matrix elements of decay process $\langle p_f,\ldots\mid p_i\rangle$, ...
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Why do objects have a Natural Frequency? [closed]

Why should an object even have a natural frequency, why not vibrate at any other frequency? This just sounds nonsensical.
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$Q$-factor for damped oscillator (not driven)?

How would this be defined? Some of the Q-factor definitions I have encountered include: $$Q=2\pi\frac{Energy \space stored}{Mean \space power \space per \space cycle}\\Q=2\pi\frac{Energy \space ...
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Why do open-closed cylinders resonate at high input impedance?

According to this paper, open-closed cylinders (clarinets) resonate at maxima of input impedance, while open-open cylinders (flutes) resonate at minima of impedance. Since acoustic impedance is ...
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What causes a harmonica note to drop in pitch (AKA bend)?

I understand how I can lower the pitch of any note on my trumpet, regardless of the volume, by slowing the rate of vibrations of my lips. But how is it that I can lower (AKA bend) the pitch of a reed ...
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65 views

Natural and Driving Frequency of a Spring-Mass System

Does $$f = \frac{1}{2\pi}\sqrt{\frac{k}{m}}$$ measure the natural frequency or driving frequency of a spring-mass system? I can't find any resources which confirm this! I believe it measures the ...
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68 views

Why is a parallel RLC circuit usually driven by a current source?

Almost always when I see an example of a parallel RLC/LC circuit diagram online, the circuit is driven by a current source instead of a voltage source. On the other hand, the series RLC is always ...
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16 views

Characteristics of acoustic resonator with a constant gain frequency response

What would be the theoretical characteristics of an acoustic resonator cavity which has a completely flat gain frequency response over 200Hz-3000Hz (Roughly the range of a violin) In other words, ...
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Does a string vibrating with hard boundaries contain harmonics of the fundamental frequency?

When the string of a violin is plucked, the resulting sound contains harmonics of the fundamental frequency. Is this an inherent property of a string with hard boundaries vibrating? Does an ideal ...
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63 views

Sound, Resonance tube experiment [duplicate]

Why surface of water behaves as a denser medium inspite of the fact speed of sound is greater in water than in air as seen in case of Resonance tube. To achieve resonance again we lower the level of ...
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Why are C, G and C all played open on the trumpet?

Why are C, G and C all played open on the trumpet? I would expect C, F# and C to be produced by adjusting embouchure as they're evenly each a half octave apart. What am I missing?
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The value of the driving frequency at which the voltage across the capacitor becomes maximum in a series RLC ac fed circuit

The circuit diagram is as shown. As per the book voltage across the capacitor is maximum during resonance that is p=1/√(LC) But what I found out is a bit different . And it is. p=√((1/LC)-(R²/2L²)) ...
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Where do pure tones occur in nature, besides harmonics?

When you sound a tuning fork, you hear an pure tone/sine wave of usually 440Hz. Yesterday, I tried hitting a table knife made entirely from stainless steel against a grapefruit. When I held it up to ...
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Why do the matrices in k-space and the final MRI image have to match?

Naturally, there is no correspondence pixel-to-pixel between Fourier space (k-space) and the final 2D image of an MRI - k-space stores the Fourier coefficients, hence each pixel in it affects the ...
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Are These Guitar Strings Demonstrating Subharmonics?

This video has a fair few instances where there is an exaggerated wiggling of the guitar strings. I rationalise this by saying its a similar effect to rotoscoping, like where wheels appear to spin ...
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Why don't transformers have capacitors?

I recently learnt about how resonance in an LC (inductor capacitor) circuit could increase the efficiency of the circuit, for application in something like Resonant Inductive Power Transfer. Excuse ...
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60 views

Feshbach resonance and the Gross-Pitaevskii equation

I have a question about Feshbach resonance and the (generalized) Gross-Pitaevskii equation. If we consider a BEC at a finite temperature $T_{BEC}$ and a static mean-field thermal cloud at temperature $...
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1answer
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Relation between shapes and vibrations

I have observed the following shape on surface of water when the bottle was standing on a cooling water machine. I was amazed by the formation because I had not seen this before. I'm not completely ...
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2answers
54 views

What does resonant frequency in the Q factor mean?

For the Q factor of a body undergoing force oscillations, does resonant frequency refers to the frequency of driving frequency or the body's natural frequency? The term resonant frequency seems to ...
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63 views

Musical Instrument that Exhibits Spherical Harmonics

A guitar string exhibits standing wave patterns when its struck, some superposition of sines and cosines, a drum head exhibits a superposition of Bessel functions when its struck. Is there any ...
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705 views

Why are there only odd numbered harmonics in one closed end resonant tube? [closed]

Why do we only have odd numbered harmonics at one-end closed tubes, however, if we do a frequency spectrum we have some periodic spikes between the odd harmonic spikes, just like the picture below ...
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Why is the Laplace Transform essentially never used when dealing with problems involving resonance?

Both the Laplace Transform and the Fourier Transform can be applied to a PDE, for example the wave equation, and used to derive a solution to the equation. But I never see the Laplace Transform used ...
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Resonances in QFT

I am a bit confused about resonances in QFT. I am reading Schwarz's QFT book and as far as I understand, if in a reaction the mass of the particle acting as a propagator is bigger than the sum of the ...
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68 views

Quantum tunneling/transmission through an infinite potential

In Shankar exercise 5.4.2 we consider the reflection and transmission of a wavefunction through a delta potential $V(x) = aV_0\delta(x)$. I understand that to mean that the potential is zero ...
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What is a correct loudspeaker connecting scheme and why? [closed]

Thinking of "what would be best shape for a subwoofer box?" i came to idea of a barrel, with its sides (or covers) "replaced" with speakers: I have stereo bass amplifier which is fed from single ...
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213 views

Why does the length of a pendulum cause different natural frequencies of pendulums in Barton's pendulum?

In Barton's pendulum, the pendulum with string that is the same length, L, as the brass bob (source of driving frequency) has natural frequency equals to the bob's driving frequency. The pendulum ...
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Why is $Q$ factor an important quantity for electrical oscillations transmitting radio waves?

My textbook says that "$Q$ factor is an especially important quantity for electrical ossicilations trasnmitting radio waves. When selecting radio and television stations it is essential that the ...
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What are the conditions for molecular,photon resonance other than same frequency?

I know that the basic condition for molecular,photon resonance is same frequency but what are the other condition for this process like phase relationship,round trip of the molecules and so.Also can ...
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1answer
60 views

Uncertainty cannot be calculated?

I'm doing an experiment on resonance. The phase difference between the driving force and the one oscillating is given by $$\varphi=\arcsin\left(\frac{y_1}{y_2}\right)$$ where $y_1$ and $y_2$ are ...
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Dispersive regime and resonator frequency pull

I have come across terms such as "dispersive regime" and "dispersive measurement" often. To understand this, I have been reading this, this, and this. In the first paper, the gist I got is the ...
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Does the resonance frequency of a cantilever beam depend on whether it is bending in-plane?

What is the in-plane resonance frequency equation for a single-beam cantilever of rectangular cross-section that is fixed on one end and has a mass M attached to the other end? Below are the only ...
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1answer
133 views

What is a complex phase shift?

In a complex methods course I am taking, we were given an equation for a particular driven harmonic oscillator where the driving force is trigonometric. I have worked out the math and obtained an ...
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2answers
167 views

What is the difference between natural, fundamental, resonant, and forced frequencies?

I'm just overall slightly confused on their exact definitions, as they get thrown around a lot.
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79 views

How LC oscillator is used for generating signals?

I have been trying to understand some practical applications of LC oscialltors and I dont seem to find much information available on net. One consistent application that I see is "LC circuits are used ...
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3answers
106 views

What happens in an organ pipe at frequencies other than the harmonics?

I learned that, at frequencies corresponding to harmonics, standing waves are formed. But what actually happens at other frequencies? Won't the reflected wave superimpose with the original wave? Do ...
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169 views

What is the effect of mass on resonance amplitude?

When a system is undergoing forced oscillations, why does reducing the mass of the system cause the frequency response curve to shift downwards? I encountered this problem in a practice paper, but I ...
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128 views

Can vibrations be used to reduce friction?

This lecture by Julius Miller got me wondering if acoustic resonance (or vibration in general) can be used to reduce friction (or stiction). The answer seems to be no based on the observation that my ...
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Negative surface plasmon decay rate

I'm calculating surface plasmon decay rate $\gamma $ as [1], $\gamma = \eta \epsilon''$ where, $\eta = (d \epsilon_{g}'(\omega)/d \omega)^{-1}|\omega = \omega_{at\:resonace}$ and dielectric ...