Talk:Resonance/Archive 1

Archive 1

Why is first picture in German in an English Article?

can we add some more detailed stuff about string resonance, tube resonance, impulse response, frequency response, stuff like that? maybe a swing set example, since that is something people understand easily. i don't know the details that well. also can we explain how the energy moves around in a resonant system? For instance... well... I don't even know a for instance. I don't understand it and I wish I did. Clearly a resonant system is passive, and doesn't create more energy than you put into it, but it somehow builds up that energy, and I obviously need this concept explained more clearly. I will do some research and help write it, but other people add stuff you know too. - Omegatron 14:16, May 21, 2004 (UTC)

Actually, should we make an article for Acoustic resonance and move some of this stuff over there? Along with the resonance bits from Acoustics. - Omegatron 15:36, Aug 6, 2004 (UTC)

Graphical equation question

(bkil 09:26, 12 July 2005 (UTC)) It might be useful to expand the equation
f=((T)/({rho}))^(1/2) / (2*L)=
=((T)/(m/L))^(1/2) / (2*L)
with these fractions
(+) =((T*L)/(m))^(1/2) / (2*L) =
(+) =((T*L)/(m))^(1/2) / (2*2*L*L)^(1/2) =
(+) =((T*L) / (4*m*L*L))^(1/2) =
(+) =((T) / (4*m*L))^(1/2)
ie.:

        ______
       /  T   |
f =   / -----
    \/  4 m L

to better visualize the relationship of the parameters, and the sentence following, that says:
Higher tension and shorter lengths increase the resonant frequency, and vice versa.

Increase in energy?

"is an increase in the oscillatory energy absorbed by a system"?

you mean an increase relative to other energy levels. resonance isnt an energy source... - Omegatron 18:11, Dec 9, 2004 (UTC)

One concept critical to understanding resonant absorption: in order to receive energy, the passive oscillator transmits. Resonant absorption might better be understood in the case of plane waves and diagrams involving diffraction patterns. If we have an incoming train of plane-waves, and if a small pointlike transmitter then sends out sphere-waves of the same frequency, and if the phase of the transmitted waves is adjusted in order to create a shadow in the region "downstream" from the transmitter... then we have resonant absorption occuring. By emitting a train of inverse waves, the "transmitter" has cancelled out some of the incoming waves; it has punched a hole in the plane waves, created a shadow, and a portion of wave-energy has gone missing. The missing energy ends up inside the point-like "transmitter." That's how resonant absorption occurs. If a passive oscillator such as an LC circuit is involved, then the oscillator is simultaneously "stealing energy" from the incoming wave while it also emits waves of its own. These concepts apply to resonant radio antennas, to resonant acoustic absorbers, and even to resonant atoms which "eat" light waves. The same explanation also applies to RLC circuits: a paired coil/capacitor acts as a passive oscillator which essentially sends out an inverse copy of the incoming signal. The two signals cancel. As a result, some energy has vanished from the original signal. The missing energy ends up inside the passive LC oscillator, and the oscillations grow larger until any further increase would "transmit" more energy than is being absorbed via the wave-cancellation process. (So, is this understandable? Too complicated?) --Wjbeaty 08:42, Apr 19, 2005 (UTC)

???

Can you draw or GIS some pictures? Passive systems clearly don't really transmit anything, so you're just using that idea as an example in some way, but I don't understand the example. - Omegatron 02:45, Apr 20, 2005 (UTC)

Ah, perhaps your first assumption is the problem. I meant what I said: passive systems definitely transmit, it's just that they cannot transmit anything more than they absorb. Also, as they are transmitting, they are simultaneously absorbing. For example, when a metal mirror reflects EM waves, the free electrons in the metal surface are oscillating coherently, and this is no different than the electric current in a radio transmitter antenna. In that sense, a mirror is an "energy source" since it radiates EM waves which it had absorbed. But obviously a mirror is not a *net* energy source. In many different systems the phenomenon of reflection is not a "bouncing" of waves, instead it's absorption combined with re-emission.

In the case of resonant absorption, the "absorber" behaves as a much better transmitter than it otherwise would, but this occurs only at one particular frequency. The "absorber" takes in wave-energy, then sends out an anti-wave which cancels out part of the incoming wave-energy, which allows the absorber to take in MORE wave energy, letting it transmit an even stronger anti-wave, etc. This is how all radio receiving antennas work. (Question: with antennas, why does a good transmitter make such a good receiver? Answer: It's because absorption is in fact based on the emission of an anti-wave. Whenever you design a good transmission antenna, you inadvertantly design a good receiving antenna, and you're amazed to find that the reception pattern is the same as the transmission pattern. ) --Wjbeaty 01:33, May 21, 2005 (UTC)

Hmm.. still confused. Reflection is not the same as transmission, and a transmitted wave cannot cancel out a received wave since they are going in opposite directions? - Omegatron 17:49, May 22, 2005 (UTC)

I reworded the definition slightly to remove the word "increase", which I admit was slightly ambiguous. --Heron 19:33, 22 May 2005 (UTC)

I must say, Wjbeaty has provided some food for thought - it will take some time to 'digest' what he has said above! W.r.t. Omegatron's question above, it is my understanding that a standing wave is due to the interaction of a transmitted and reflected wave where the nodes of the standing wave are due to the destructive interference of the two waves travelling in opposite directions.

Interestingly, it is always possible to obtain the solution for a system with reflection at the boundaries using the 'Method of Images' where each reflected wave is replaced with a transmitted wave from a source outside the boundaries of the system. Perhaps this is the key to Wjbeaty's post above.

One last comment - As mentioned above, a good absorber is necessarily a good transmitter. Consider the ideal Black body. Alfred Centauri 14:43, 21 August 2005 (UTC)

Split into different articles

What do people think about having this article just explain the basic idea of resonance, then have seperate articles on Mechanical resonance, Electrical resonance and Acoustic resonance? There is certainly enough of a scope to warrant splitting this article into four different articles, and I think that making four different articles would more likely encourage those who know about one specific field to expand them. --Nathan (Talk) 03:49, 30 December 2005 (UTC)

Agreed. — Omegatron 23:59, 30 December 2005 (UTC)

Right, I'm gonna do it. It seems a very logical thing to do, and one other person agrees. I don't think there's a way of moving sections (to avoid destroying the history), so I'll just have to copy and paste. I'll leave notes in the edit summaries, though.--Nathan (Talk) 01:08, 31 December 2005 (UTC)

I've done the cutting and the pasting. Now those three articles need introductions, and some of the See Also items need to be cut and pasted as well. I'll do some of it another time if nobody beats me to it. *hint* --Nathan (Talk)

Rice resonance?

Is the link to the YouTube video actually an example of resonance and its effect on rice? It seems to me there is no reaction between the vibration of the sound and the natural vibrations of the rice but rather the rice is just creating a visual pattern of the areas of high and low vibration on the speaker surface. But maybe I'm just not clear enough on the concept.— Preceding unsigned comment added by 24.5.209.192 (talk • contribs) 22:36, 29 June 2006

Tacoma Narrows Bridge not destroyed by resonance

http://www.kuro5hin.org/?op=special;page=random#bridge

Here someone explains that the Tacoma Narrows Bridge is not a good example of resonance. Should the reference (or perhaps the whole paragraph) be removed?

The destruction of the Tacoma Narrows Bridge was indeed not caused by resonance, but the article is not claiming that it is. However, the bridge did suffer from resonance at other times, which is where the nickname "Galloping Gerdie" came from. At least, that is my understanding from reading Tacoma Narrows Bridge; perhaps a mechanical engineer can correct me. You may be right that we should not mention the Tacoma Narrows Bridge because it is a rather confusing example. However, the London Millennium bridge seems to be a proper example. -- Jitse Niesen 17:06, 7 Feb 2005 (UTC)

The Tacoma Narrows bridge was destroyed by resonance, but not in the way we might imagine. If we place an object in a flow of air, at certain wind speeds the downstream air turbulence takes the form of periodic counter-rotating vortices called a "Von Karman vortex street." (Imagine a flapping flag, then imagine a series of tornadoes shed by the flag and which continue far downstream.) At just the right wind speed the periodically varying wind direction and pressures caused by the wake-turbulence would have the same frequency as the bridge. Imagine a flapping flag which is connected to a pendulum: at certain wind speeds the flap-frequency would match the pendulum frequency, and the pendulum would go wild! If the pendulum frequency was very low, then only a very slow air motion would hit the right frequency. So, the bridge was resonantly pumped into motion by puffs of air, but these puffs of air were coming from downstream, and they were part of the natural (but invisible) turbulent wake that exists behind most objects exposed to wind. The same effect is often seen in power lines on days with almost no wind. The lines start swinging mysteriously because the very slow wind is creating some slow turbulence, and there is an "AC signal" in the turbulent air which matches the natural frequency of the swinging wires. The wires are pumped into large motion by their own air turbulence. --Wjbeaty 01:43, May 21, 2005 (UTC)

You are wrong Wjbeaty. I corrected the wikipedia article. I added the most important reference about that mistake that the Tacoma failed due to resonance. It failed due to fluttering. Robert Scanlan, father of bridge aerodynamics wrote an article on the subject... see main text:

http://www.ketchum.org/billah/Billah-Scanlan.pdf

Diego Torquemada 07:51, 5 April 2006 (UTC)

After browsing the linked document, it appears to me that, in EE language, the poles moved into the RHP. That is, with the wind as an energy source, the bridge became an oscillator. I assume that's what self-excited means in this context - there is an output at some frequency without a corresponding input at that frequency.

BTW, Diegotorquemada, beginning a sentence with "You are wrong..." is a great way to make friends around here. Wish I had thought of it. Alfred Centauri 03:44, 6 April 2006 (UTC)

sorry Alfred and Wjbeaty, next time I will measure better my words. What you say about the poles is right... when the poles of the bridge go to the right hand side, and have imaginary parts, fluttering is produced. There is another failure for bridges, that is when the pole in the RHS is purely real. In this case a failure called "divergence" is produced. It can be understood as a really flying bridge, because the deck just lifts on the presence of strong wind, making it literally fly, and since the tension in the hangers is lost, the bridge collapses by overturning. Diego Torquemada 07:42, 8 April 2006 (UTC)

disambiguation

It seems like this page could be a disambiguation page, rather than pointing to a separate disambig page. It doesn't seem like this page is overpowering enough (with respect to other resonance pages) to have control of the main title. Fresheneesz 02:20, 19 May 2006 (UTC)

Resonance is important as a general concept, so it seems like it deserves its own page. A page describing Q, energy transfer, etc, seems useful, to present the overall idea. I'm not sure we need to introduce quantum field theory to do that, I'd be happy with a mechanical pendulum.

technical link

This needs to be more accessible. Telling the reader resonance in quantum field theory could be "this or that" without clarifying the distinction, or "see also [some esoteric topic]" isn't a good style. John Riemann Soong 00:47, 28 July 2006 (UTC)

I agree. The Quantum field theory section needs some serious work; it is practically incomprehensible as it is now. HEL 02:23, 15 October 2006 (UTC)

I rewrote the quantum field theory section and tried to make it less technical. If I've stepped on anyone's toes, I apologize; please let me know! The link to relativistic Breit-Wigner distribution now contains an (I hope) clear description that includes the propagator with its complex part. HEL 00:53, 20 October 2006 (UTC)

Differential Equations?

Perhaps there should be a mention of how resonance is the result of poles in DEs, and a derivation of one of the resonant freqency formula (f=1/sqrt(LC) or some such). —The preceding unsigned comment was added by 141.213.209.215 (talk) 06:38, 17 January 2007 (UTC).

Copyright?

The text about quantum resonance is a copy of this text. Copyright violation? --ojs 21:07, 2 May 2007 (UTC)

Apparently so. [1] May 03, 2005 vs [2] 4 July 2005. Removed the section. Femto 13:02, 3 May 2007 (UTC)

Triple-alpha process

I recently attended a lecture given by John Polkinghorne in which he mentioned Fred Hoyle's prediction of a resonance being required for the fusion of Helium 3 to Carbon 12. As this is a very notable example of the importance of resonance in nuclear physics and astrophysics, I have added a link in the see also section. DFH 13:12, 7 May 2007 (UTC)

Guess this is as good a place as any to point out that I removed all references to quantum field theory, etc., as this material was not directly relevant to the subject at hand (mechanical & electrical resonance). The problem is that while particle physics uses the same term ("resonances"), it does not have the same meaning as the subject being discussed here, and should not be mixed up. Separate articles, perhaps? +ILike2BeAnonymous 18:33, 8 May 2007 (UTC)

News on this

Hi, most of you have probably seen the news that resonance is a well proven way of transferring electricity. Someone could add that? (then this article would need to cross reference Nikola Tesla too. 202.57.142.229 01:40, 8 June 2007 (UTC)

Series Resonance circuit

I'm having a difficulty in our topic now in our subject electrical circuits. Our topic is about series RLC resonance ciruits. Our instructor told us to derive a formula on how to get the freqeuncy when the voltage of the inductor is in maximum and also the frequency when the voltage of the capacitor is at maximum.I hope you can help me out in here.I'm really having a hard time doing this. Thank you! —Preceding unsigned comment added by Marjoyumul19 (talk • contribs) 02:29, 31 January 2008 (UTC)

On expanding the quantum mechanics section

It would be nice if someone could talk about how the Lorentzian is used in Fermi's Golden Rule when dealing with finite lifetimes. That is definitely a resonance issue. Zylorian (talk) 03:04, 8 April 2008 (UTC)

Should "driving frequency …" read "sinusoidal driving function" in section on Theory?

My intuition is that the phrase "driven with a driving frequency $\omega$" should be rewritten as something like "driven by a sinusoidal function with frequency $\omega$", following the formula for $I(w)$ in the section on Theory.

That's my intuition, but I'm not expert enough to make the "correction" (nor do I have a reference). —Preceding unsigned comment added by W.F.Galway (talk • contribs) 14:18, 18 February 2009 (UTC)

Recent changes to this article

Recently, I added a bunch of material about types of resonance in physics. Some of this was of material that was split out earlier. I am not trying to step on toes and undo the work you have done here. (I, myself, try to follow a less is more approach and try not to take expanding an article lightly.) My goal is to unify all of the oscillator articles more tightly. This is part of a larger scheme (dastardly plan?) that I have outlined in harmonic oscillator. Things that I want to do yet are: 1. figure out what to do with electric resonance. Is it just electronic oscillator and RLC, etc.. or should it include electrical resonant cavities and wave guides as well. Wikipedia is evil, editing one page leads you to another to another. 2. add a section on the quality of the resonance as determined by Q factor, damping ratio, oscillator line width, and attenuation. I am hoping for a short blurb on each and a table of the relationships between them 3. expand the lead slightly 4. clean up my mess

Number 2. in particular may be a little controversial which is why I am discussing it here. The comparison needs to be done someplace, but I am only 95% sure this is the article to do it in. It is the best I can come up with. Damping might do, but damping does not include forced motion. Oscillators may be a better place, but that redirects to Oscillation for which this discussion doesn't quite seem to fit. I want to avoid creating, yet another page to maintain, if possible.

Any ideas would be greatly appreciated. Again my main goal is to unify the oscillator pages more tightly and to make navigation and finding information more easy. TStein (talk) 06:25, 18 May 2009 (UTC)

Sounds like a great idea. It's mostly a confusing and largely unrefernced mess at this point. Dicklyon (talk) 15:51, 8 August 2009 (UTC)

Theory

I'm not really familiar with the parameterization by linewidth, the use of capital gamma and omega, etc. And I'm a bit confused by the use of this "Lorentzian formula" here. The formula gives the amplitude as symmetric about the center frequency of capital omega. But the "transmissibility" or whatever it's called in the lead graph is clearly not symmetric about the center frequency -- though is is symmetric about zero frequency, which the theory formula is not. Probably these are both correct with appropriate interpretation, but I'm familiar with the form in the graph, not the other one, which appears to treat negative frequencies differently from positive frequencies. Since there's no source for this theory, I'll look for one, or replace it with a sourced one that I like better. Dicklyon (talk) 15:55, 8 August 2009 (UTC)

I think I've found the answer: this book derives the Lorentzian shape after making the "resonance approximation" that's only valid near resonance. So we should put the right formula first, then follow with the approximation for near resonance, yes? Dicklyon (talk) 16:16, 8 August 2009 (UTC)

Resonanc stabilization from chemistry

I haven't tried to find a citation, and maybe Galileo is a good place to look, but the general principle of "resonance" is actually due to energy match or degeneracy. This attribute is what allows an oscillation mode amplitude to grow or extract energy from the driving source. In chemistry, this degenerecy of energry levels leads to stabilization, see benzene for example. I'm currently adding stuff to shape resonance and wanted a definition for resonance. Nerdseeksblonde (talk) 15:29, 14 August 2009 (UTC)

sympathetic vibration

Aloha all

With regard to the phenomenon of drone strings. I have never been able to find an answer to this question. Would it work in vacuum? ie is sympathetic vibration dependent on a medium (air in this case).

cheers kai Makenakai (talk) 06:49, 21 September 2009 (UTC)

Will not work in vacuum. Binksternet (talk) 14:46, 21 September 2009 (UTC)

There are ways it can work in a vacuum -- sympathetic vibrations of strings if they're attached to a structure that can propagate vibrations from one string mount to the other. Some mechanism or medium of energy transport is needed, but it doesn't need to be air. Dicklyon (talk) 06:25, 22 September 2009 (UTC)

Agree with the above. For example in guitar, the vibrating strings will constantly change the tension of its support, and this will in turn parametrically drive the other guitar strings. This is different from directly pushing the strings by airwaves. --Nabo0o (talk) 18:57, 2 November 2009 (UTC)

Electromagnetic Resonance link

This link in the third paragraph links to Electromagnetic radiation. Shouldn't it go to something that actually gives an example of Electromagnetic resonance like Antennas#Resonant_frequency, resonator#Cavity_resonators or similar? The word resonance or resonant does not even appear in the Electromagnetic radiation article. --220.101.28.25 (talk) 20:59, 14 December 2009 (UTC)

Fundamental vs. Resonant vs. Natural Frequencies / Modes

Recently I've participated in several discussions which became convoluted because of misunderstandings of how these terms related to each other: fundamental frequency, resonant frequency, natural frequency, modes. If more then one of these frequencies exist for a structure and if only one exists for each degree of freedom were also unknown. Perhaps a paragraph highlighting some of this could be added? 12.188.106.66 (talk) 18:20, 17 December 2009 (UTC)

Vibrational energy???

It will be better to use elastic potential energy. — Preceding unsigned comment added by 217.108.131.69 (talk)

The sentence refers to all forms of resonance, not just mechanical but electronic too. The point I was trying to get across was that the peculiar effects that occur in oscillating systems at their resonant frequencies (large amplitude response to small driving force, large phase changes, "ringing" transient response) occur because the system stores energy at the resonant frequency, oscillating back and forth between kinetic and potential energy, but not at other frequencies. --Chetvorno^TALK 02:13, 15 October 2010 (UTC)

Phase change on reflection

There is often a phase change on reflection, right? Shouldn't the equation take that into account? 198.109.220.6 (talk) 15:07, 8 November 2011 (UTC)

'Resonance frequency' vs 'resonant frequency'

An editor recently changed all instances of "resonant frequency" in the article to "resonance frequency", citing as source Hunt, Frederick V. (1971). "Resonance versus Resonant". Journal of the Acoustical Society of America. 50 (2A): 435. doi:10.1121/1.1912654. Retrieved 17 April 2012. which points out the former term is ungrammatical. This issue has been debated above. I think, particularly in scientific articles, WP should adhere to the most common usage, rather than be guided by grammar. "Resonant frequency" is by far the more common usage. I googled the two forms and got 5,960,000 hits for "resonant frequency" versus 1,280,000 for "resonance frequency". The former term has been used for at least 170 years 1 and I doubt if it is going to become extinct now. It would be nice if the neologisms that science invents were grammatical, but the more important requirement is that they are used consistently. If there are two forms, readers (particularly nontechnical readers) may assume they mean different things. We serve our readers best by using the more common form, rather than trying to be grammar police. I think "resonant frequency" should be used in this article (with a note at top that "resonance frequency" is a synonym). --Chetvorno^TALK 16:03, 24 April 2012 (UTC)

I have mixed feelings about that. If the usage were overwhelming on one side, there'd be no question, but in recent years the usage has become nearly equal (see book ngrams). How we serve our readers best is a matter of debate in this case; I can see a case for the more modern grammatical alternative. Dicklyon (talk) 16:41, 24 April 2012 (UTC)

Hunt has not been so influential as he might have wished. The "resonant frequency" is still very widely used, far more widely than "resonance frequency". I think we should go with common usage. Binksternet (talk) 17:17, 24 April 2012 (UTC)

a Pendulum doesnt really resonate

true resonance requires that the restoring force be proportional to the displacement. the restoring force for a pendulum is proportional to the sin of the angle (which can be thought of as the displacement of the mass. ie. the distance it moves along its path). just-emery (talk) 02:48, 6 July 2009 (UTC)

That's true. But for small amplitudes of a few degrees deflection, which are used in all timekeeping pendulums, the restoring force is very close to linear (proportional to the deflection). Pendulums show all the characteristics of resonance: resonant frequency, bandwidth, and Q, and were the first resonant systems used by man. No vibrating system has absolutely linear restoring force, and the inherent nonlinearities in "classical" harmonic oscillators such as masses on springs is often greater than the nonlinearity of a pendulum limited to small swings. --Chetvorno^TALK 05:06, 6 July 2009 (UTC)

Maybe this should be added to the end of the article. just-emery (talk) 08:59, 6 July 2009 (UTC)

I am going to leave the dubious tag up for a short while so people can commont on it. After all its only been up for a few days. However, I'm happy with the article as it now reads. I see no reason not to include a pendulum in the article as long as there is a disclaimer somewhere in the article stating that the restoring force for a pendulum is actually sin(displacement). just-emery (talk) 00:22, 7 July 2009 (UTC)

By what definition of resonance does the restoring force need to be linear? What's wrong with a nonlinear resonator? Dicklyon (talk) 15:39, 8 August 2009 (UTC)

Strictly speaking the theory of resonance comes from the solution of linear differential equations (which should probably be in this article). The resonant frequencies are the eigenvalues of linear equations. Nonlinear restoring force causes distortion, resulting in the generation of harmonics, shifting energy from one frequency to another. Only in linear systems are the energies in the different resonant modes independent of one another. --Chetvorno^TALK 11:12, 28 August 2012 (UTC)

But nonlinear resonance is a valid concept, too. And the frequencies are not eigenvalues; they are parameters of eigenfunctions. Dicklyon (talk) 12:23, 28 August 2012 (UTC)

Yeah, I guess it can all be called resonance. According to Google, the natural frequencies of a system are the square roots of its eigenvalues. Do you think we should add some of this to the article? All it has is resonance curves, without saying much about where they come from. --Chetvorno^TALK 13:11, 28 August 2012 (UTC)

Pushing a swing is not an example of resonance

People who are not familiar with the idea of a resonance frequency, commonly believe that pushing a swing at the right time is a good example of resonance frequency. I would argue that it is not. Moreover, I believe that this example can lead to confusion. For example, if I push a swing every other time, the frequency I push the swing at is only half of the resonance frequency. However, the forces I apply to the swing will still add in a constructive manner, causing the swing to move higher. From this example, I may believe that the solution to a simply harmonic oscillator being driven by a sinusoidal driving function that is half the resonance frequency behaves qualitatively like a simple harmonic oscillator being driven at the resonance frequency, however, this is not true. The source of this confusion is that the force I apply to a swing is not a sinusoidal driving force.

When discussing simple harmonic oscillators, the only driving forces that have trivial solutions are sinusoidal driving forces, for example: $F(t) = \sin ( \omega t)$. Because sinusoidal functions form a orthogonal basis set, when presented with a driving force that is not sinusoidal, we can write the driving force as an integral (sum) of sinusoidal functions. This is called the inverse Fourier Transform and it is typically written in terms of a Fourier Transform. Since all driving forces can be written in terms of sinusoidal function, once we know how the simple harmonic oscillator behaves for sinusoidal driving forces, we can solve the simple harmonic oscillator for all driving forces. Because of this, we often study the solutions to the simple harmonic oscillator being driven by a sinusoidal force. The term resonance frequency refers to a frequency of a sinusoidal driving force that results in solutions that are qualitatively different than the solutions you get for other sinusoidal driving forces. Thus the term resonance frequency assumes a sinusoidal driving force. When pushing a child on a swing, you impart a short impulse to the child. Moreover, the force you apply is always in the same direction. Clearly this force is not sinusoidal. Furthermore, if this driving force were decomposed into sinusoidal forces, we would find that the component of the Fourier Transform that correspond to the resonance frequency is not much greater than the components that correspond to the off resonant frequencies. — Preceding unsigned comment added by 76.104.20.225 (talk • contribs)

Actually, it's not a bad example if presented carefully. The resonant system pretty much picks out that small component at the resonance frequency, and pretty much ignores the rest. Dicklyon (talk) 05:03, 28 May 2012 (UTC)

Yes, resonant systems are frequently driven with impulsive drive forces, as in electronic oscillators, pendulum clocks, and nuclear magnetic resonance. One of the features of a high-Q resonant system that a swing illustrates well is that it can convert a nonsinusoidal drive force into sinusoidal motion. --Chetvorno^TALK 08:55, 28 May 2012 (UTC)

free vibration:When a body is distributed from its mean position and allowed to vibrate freely on its own then frequency of vibration is known as natural frequency and osicalliations are called as free vibrations — Preceding unsigned comment added by 203.194.97.194 (talk) 17:06, 7 October 2013 (UTC)

"Tendency" ?

The lead definition says that resonance is a 'tendency', but in numerous other places (even the second paragraph of the lead), resonance is said to 'occur', or the word 'phenomenon' is used. I would like to suggest that 'tendency' is inappropriate in the definition; if taken literally it seems to indicate that resonance is a property of a system, whereas in fact it is better to say that resonance is something that happens - it is a phenomenon which certain systems sometimes exhibit. I would like to suggest this as an alternative - paraphrased from "Physics for scientists and engineers - 4th edition, RA Serway, 1996, Saunders College Publishing, Philadelphia, etc, p 508: "A wide range of physical systems, including stretched strings, organ pipes, inductor-capacitor circuits, etc, are capable of oscillating in one or more modes of natural oscillation. If such a system is made to oscillate artificially by applying an appropriate stimulus, the amplitude of the resulting oscillatory response is greatest when the frequency of the stimulus is equal, or nearly equal to one of the natural frequencies of the system. These peaks of response at particular frequencies are called resonances, and the frequencies at which the maximum responses occurs are resonant frequencies". G4oep (talk) 10:27, 15 January 2015 (UTC)

I think this is splitting hairs. In my opinion the lead sentence: "...resonance is the tendency of a system to oscillate with greater amplitude at some frequencies than at others." is excellent for a general encyclopedia. It defines resonance in simple words in a single declarative sentence for nontechnical readers, without resorting to the scientific buzzwords and multiple clauses of the Serway quote. I wouldn't mind introducing the idea that when a system is made to oscillate "artificially" the amplitude is maximum at the natural frequencies into the first paragraph, but I don't see any reason to change the lead sentence. --Chetvorno^TALK 11:26, 15 January 2015 (UTC)

Resonant frequency or resonance frequency???

It appears that there is no such thing as a resonant frequency:

http://users.ece.gatech.edu/~mleach/misc/resonance.html

I recommend that the various 'resonant frequency' terms in the article be replaced with 'resonance frequency'. Alfred Centauri 02:41, 21 August 2005 (UTC)

I don't.

"The frequency at which resonance occurs is called the resonant frequency." -- A Dictionary of Physics. Ed. Alan Isaacs. Oxford University Press, 2000. Oxford Reference Online. Oxford University Press.

"At the resonant frequency, ..." -- "resonance" entry, Britannica Online, 2005.

"at the resonance frequency" -- "resonance" entry, Newnes Dictionary of Electronics on xreferplus, 2005.

"The resonant frequency is the frequency at which ..." -- "resonance" entry, The New Penguin Dictionary of Science, on xreferplus, 2005.

"is said to be .. the resonant frequency" -- "resonance", Penguin Dictionary of Physics, 1982.

"resonant frequency" (headword) -- Chambers Science and Technology Dictionary, 1988.

"resonant frequency" (headword) -- OED2, with citations from 1925, 1934, 1964.

I think FV Hunt is being unnecessarily pedantic. Most authorities write "resonant", but a few write "resonance". Who cares? It's only a shorthand term for a real concept - it doesn't alter the concept itself. It reminds me of the famous pedant C.P. Scott, who complained that television would never catch on because it was a hybrid of Greek and Latin roots. Hunt has a point, and perhaps "resonance frequency" is more accurate than "resonant frequency", and if you agree with him then you can write the former, but it's not a good enough reason to go changing what others have written. --Heron 11:46, 21 August 2005 (UTC)

I agree that no one will be confused by the use of 'resonant frequency' instead of 'resonance frequency'. On the other hand, it is my opinion that the author(s) of an encyclopedic article should and would care about 'getting it right'. After all, you do agree that "Hunt has a point". While I question your description of the changing of the word resonant to resonance as a 'rewrite' of the article, I do see your point. Accordingly, I have added the link above to the 'External Links' section of the article. Alfred Centauri 13:14, 21 August 2005 (UTC)

Thank you for accommodating my objection, Alfred. I accept that the word "rewrite" was an exaggeration and, to be honest, I suppose it won't hurt if you do decide to change the phrase throughout the article. My only concern is that you don't start telling people that they are "wrong" for using "resonant", as I think the distinction is too pedantic to matter. --Heron 14:59, 21 August 2005 (UTC)

Agreed. I hope I haven't developed a reputation on Wikipedia for nitpicking for any reason other than to spur intelligent conversation. Alfred Centauri 16:47, 21 August 2005 (UTC)

Here is how i look at it: A frequency doesn't resonate any more than a curve resonantes, a circuit can resonante hence resonance frequencies and resonance curves and resonant circuits. :>) TomPoindexter 20:40, 23 January 2007 (UTC)

I feel when technical terms are defined in an encyclopedia for nontechnical people, it is especially important to respect actual usage. In technical fields, there is a high rate of neologisms. It would be nice if they were all grammatical, but it is more important for the meaning to be unambiguous. Readers not familiar with resonance could easily assume the two forms refer to different things. I googled "resonan frequency" to pick up both terms, eliminated ambiguous and repetitive hits, and counted. Out of the first 44 there were 27 occurrences of 'resonant frequency' and 17 of 'resonance frequency'. I'd suggest mentioning in the article that both terms are used. --Chetvorno 10:30, 21 October 2007 (UTC)

In terms of English grammar, an adjective (e.g. 'resonant') is required if the intention is to qualify a noun (i.e. to say what kind of 'frequency' you are talking about). G4oep (talk) 10:46, 17 January 2015 (UTC)

It's not just grammar, but usage; resonant is not an adjective appropriate to the noun "frequency" (frequencies aren't resonant). Thus, given the intent of Wikipedia (or any encyclopedia) being to educate the reader, using incorrect terminology does the reader a disservice. From a quick read, one might come away with the impression that resonance might be a characteristic of a frequency (rather than the other way around). Regardless, there doesn't seem to be any reason not to correct the wording. Paraphrasing the point of an editor above, reinforcing an incorrect usage (popular or not) is not helpful. However, it is a good idea to note that the incorrect usage is common. Jbusenitz (talk) 21:55, 6 February 2015 (UTC)

Is it incorrect? What rule of grammar would I find in a grammar textbook that is being broken here? You say that frequencies aren't resonant (without justifying that claim), but frequencies aren't resonance either, and that latter statement is surely ungrammatical. SpinningSpark 16:23, 9 February 2015 (UTC)

Read again; "it's not just grammar". My point is that is what is communicated to the reader. There are sufficient references to support that above. Unless you are prepared to justify your claim that "frequencies aren't resonance either", I suggest we engage in a more constructive discourse. It was never implied that "frequencies are resonance"; the appropriate rewording would be "frequency of resonance". To address the other points above, having a career in an industry which uses this term quite a bit, I certainly haven't seen "resonant frequency" used more commonly than "resonance frequency" (in multiple companies). But at any rate, is there some unknown pillar of Wikipedia that espouses tyranny of the masses; i.e., promoting mistakes, if popular, as optimal wording for an article? Jbusenitz (talk) 02:58, 10 February 2015 (UTC)

Even if it is ungrammatical, "resonant frequency" is simply an idiom used in engineering. There are ungrammatical idioms used throughout English (how about "running for office"?). Is this really worth our time? Over on Talk:Electric current there was a similar endless, silly, pointless debate about the idiom current flow in a circuit. Editors argued that an electric current is a flow of charge, so current does not flow; others argued that it was widely used idiom and the redundancy improved understanding. After months of spilled ink, wasted man-hours, personal epithets, useless research, and citations of conflicting sources, no conclusion was reached; everybody just got tired. The irony was that a few changes of usage in a Wikipedia article were not going to make any difference anyway. There is no end to this type of debate. --Chetvorno^TALK 05:50, 10 February 2015 (UTC)

It depends on the goals; inform the reader, or echo is perceived to be common, if incorrect. I have yet to see any justification for using the "-nt" version, idiomatic or not (is it really an idiom?). Again, to the apparent goal of an encyclopedia, it would seem that using the "-nce" version is most informative, and needn't be misleading if the "-nt" version is mentioned as well. I would not want to mislead someone into thinking that a frequency is somehow resonant. Jbusenitz (talk) 21:47, 10 February 2015 (UTC)

The ultimate justification for a specific term is usage. However, it is not too difficult to see why "resonant frequency" became the dominant form and was virtually the only usage for 100 years. In the context of physics, electrical engineering, acoustics, etc. the concept "resonant frequency" is most often applied to a particular piece of apparatus; a resonator, which is "resonant" at a particular frequency, such as a quartz crystal, LC circuit, dipole antenna, laser cavity, or loudspeaker cone, rather than the abstract process of "resonance". Thus "resonant frequency" is preferred, short for "frequency at which this device is resonant", rather than the less specific "resonance frequency" which means "frequency at which resonance (in the abstract) takes place" --Chetvorno^TALK 23:36, 10 February 2015 (UTC)

There must be many examples in English of adjectives that on their face don't appear appropriate to the noun they modify; but they're hard to think up. Certainly "resonant frequency" here doesn't mean the frequency is resonant, but rather that the system is resonant at that frequency. I agree that "resonance frequency", meaning the frequency of a resonance, is more logical, but less idiomatic. Usage is shifting gradually toward that more logical form, but the traditional idiom still is in the majority. I could go either way, so I won't join the fight. Dicklyon (talk) 06:25, 10 February 2015 (UTC)

Recent changes to lead

Recently the lead has been changed from

In physics, resonance is the tendency of a system to oscillate with greater amplitude at some frequencies than at others.

to

In physics, resonance is a phenomenon that consists of a given system being driven by another vibrating system or by external forces to oscillate with greater amplitude at some preferential frequencies.

I think the new wording is not as good, for two reasons: (1) The term resonance is not applied only to driven systems, but is also used for free oscillations excited by initial conditions. (2) The wording gives the misleading impression that resonance is something imposed on one system by another, and fails to communicate the idea that the frequencies of greater oscillation amplitude are an inherent property of the oscillating system. I'm not saying it couldn't be improved, but I felt the original wording was a good, simple introduction which conveyed the idea well to general readers. Anyone else have an opinion? --Chetvorno^TALK 19:34, 7 April 2015 (UTC)

But neither this sentence nor the dominant article content reflects that

"Resonance also occurs in quantum mechanics"

Sure, but does this description apply to quantum systems without misleading? I think it would require an explicit qualification as a "semiclassical heuristic" Furthermore, only one subsection of the article addresses quantum systems, and the rest of it isn't now qualified by the "classical" restriction. Layzeeboi (talk) 18:31, 10 February 2017 (UTC)

But isn't it far more misleading to say that resonance is a phenomenon of classical physics and doesn't occur in quantum mechanics, as your wording does? The difference between classical and quantum mechanical resonance is far too complicated a topic to go into in the introduction, and I don't see any need to mention it. The qualification "semiclassical heuristic", will just confuse general readers. The introduction doesn't go into the differences between mechanical and electromagnetic resonance, either. --Chetvorno^TALK 19:14, 10 February 2017 (UTC)

I expect that you may agree that false statements are more serious than possibly misleading statements. I think that the present statement as you have reverted it is false:

In physics, resonance is a phenomenon in which a vibrating system or external force drives another system to oscillate with greater amplitude at a specific preferential frequency.

This sentence purports to apply to all of physics, which is untrue. Consider the figure and last sentence in this article section. Those peaks at low energy in the figure are neutron resonances. There is no modern model of these resonances in which a vibrating something is driving another system. Even in this older book about the theory of such resonances, this concept does not appear.

My proposed change " In classical physics, resonance is…" results in a sentence that is at least correct. You worry that it may seem to imply that the concept of resonance does not appear in other branches of physics. Any such implication would be a fault of the entire lede, similar to the fault that I was trying to mitigate. I think it is necessary to mention (briefly) the different meaning in quantum physics, which dominates much, or maybe even most, of modern physics. For example:

In classical physics, resonance is a phenomenon in which a vibrating system or external force drives another system to oscillate with greater amplitude at a specific preferential frequency.

In quantum physics, resonance refers to an unstable (short-lived) state of a system that is more readily excited by some particular process than other states with nearby energies. 

Layzeeboi (talk) 22:39, 11 February 2017 (UTC)

If the two meanings are not really the same, they should not be defined as the same. If the article covers both, they should both be mentioned at the very beginning—either defined universally for the parent subject area or individually and specifically for each sub-area. Is there some unifying aspect that can be mentioned first, followed by the separate aspects? DMacks (talk) 22:46, 11 February 2017 (UTC)

I agree with the principles that you state. I think attempting to include a unifying aspect could result in less clarity; the application of this term for quantum systems reflects the personal thought processes of some pioneer(s) in this area maybe 80 years ago, who didn't worry about accessibility for a wider audience. Neutron excitation is more analogous to hitting a classical bell with a hammer. Although the hammer itself doesn't vibrate, the bell responds at its resonant frequency, but I doubt that this response to an impulse is what we usually mean by a resonance, which is presently captured by the lede. For example, the bell would also respond to an audible tone close to that frequency. Layzeeboi (talk) 22:59, 11 February 2017 (UTC)

It's all the same. In a linear, or nearly linear, system, the ringing due to an impulse is one way to look at resoance, and the preferential response to coupling near a certain frequency is another. But these are not different things, even in the QM world. The QM guys mostly just don't talk about it that way. Dicklyon (talk) 23:07, 11 February 2017 (UTC)

I agree. I understand that WP should reflect how most folks "talk about it". Layzeeboi (talk) 23:18, 11 February 2017 (UTC)

I forgot another important distinction between quantum and classical resonances. In the quantum context, "resonance" may be applied to any short-lived excitation with significant spread in energy, in any of several modes, not only vibrational but also collective excitationss such as rotational, scissors, or single-particle (nucleon), two-particle,… . Layzeeboi (talk) 00:35, 12 February 2017 (UTC)

Classical resonance can also be in any mode, such as rotational, electrical, scissors, waves on a string, orbital, all kinds of things. Dicklyon (talk) 02:16, 12 February 2017 (UTC)

I agree that the statements above are probably too narrow; and also that the distinction between classical and quantum should not be a top-level distinction. Dicklyon (talk) 02:17, 12 February 2017 (UTC)

I see that my list of examples may have weakened my case. That list of quantum modes usually all refer to theory. All that one usually observes is a peak in an energy spectrum that has a spectral linewidth, indicating that the system prefers to absorb and re-emit energy quanta similar to certain amounts. That's all that we really know, unless we observe the characteristics of the decay products. So a quantum resonance is defined in terms of (imperfect) energy quantization. Classically, one can observe that the system prefers to (continuously) store or release energy at certain frequencies (and one has the luxury of inspecting the system microscopically to identify modes.) Hence I think that we need a top-level distinction that classical resonance is identified by characteristic frequencies, while quantum resonance is identified by characteristic energies. Time and energy are closely related in quantum mechanics. Layzeeboi (talk) 03:58, 12 February 2017 (UTC)

But in QM, frequency is energy, so they're very much the same. Time and frequency are related by Fourier transform, inducing an uncertainty principle. It's just math. Dicklyon (talk) 06:36, 12 February 2017 (UTC)

This comment seems facile to me. (Are you just teasing us?) I've never known a physicist who thinks quantum mechanics is "just math". It introduced a profoundly different view of physics. It is probably considered the most enigmatic established theory. Feynman said very publicly "I think I can safely say that nobody understands quantum mechanics". Here is the evolving perspective[3] of Weinberg after a long career working with the tools of quantum mechanics. Layzeeboi (talk) 08:49, 12 February 2017 (UTC)

Maybe I misunderstood you. What do you propose that "in QM, frequency is energy" implies for the article?

I can assure you that physicists working with quantum systems don't usually think of time or frequency when they discuss a resonance in an energy spectrum. The classical and quantum communities think and speak about resonances differently. Why shouldn't they share the lede? Layzeeboi (talk) 09:49, 12 February 2017 (UTC)

Then why do they use the same word, resonance? I agree with Dicklyon. For me, I think the point is that the underlying mathematics is the same. Resonance is a phenomenon that occurs in systems that are governed by underdamped linear differential equations. In mechanical resonance its Newton's law, in electrical resonance its Maxwell's equations, in quantum mechanical resonance its the Schrodinger equation. The same mathematical techniques, and the same (or equivalent) terminology, are used in both classical and quantum resonance: resonant frequencies, damping, time constant (only in QM it's called "lifetime"), resonance width, Q factor, frequency spectrum, superposition, eigenvalues and eigenvectors. In this encyclopedia article aimed at general readers, I think it would be misleading to say in the intro that the fundamental idea "resonance" is different in quantum mechanics. --Chetvorno^TALK 15:25, 12 February 2017 (UTC)

They talk of energy. But they do also realize that in a quantum wave function, energy and frequency are the same thing, related my Planck's constant. Dicklyon (talk) 15:44, 12 February 2017 (UTC)

And I didn't say QM is just math; but the uncertainty principle is; it's a relationship on things related by a Fourier transform (or roughly equivalent transform in a different space). Energy is Planck's constant times the frequency of the wave function; not just for photons; and time is the variable related to that via the transform; no difference between classical and QM there. When physicists talk about the width of a resonance using a Cauchy–Lorentz distribution, that's not different from the "universal resonance curve" of Frederick Emmons Terman; you can label the axes in whatever units you prefer. Dicklyon (talk) 04:36, 13 February 2017 (UTC)

I'm hoping here to hit "reset". I realize that we may have drifted off topic. There is no need to discuss our own understanding of "resonance". We need a consensus on only what cited reliable sources indicate about the modern understanding and usage of the term. I think that there is clear evidence that different branches of physics use this term differently. I think that WP articles should reflect that. The historical reasons for this difference may be relevant only for possible "History" subsections. I offer evidence about the meaning of "resonance" in nuclear and particle physics, for which academic sources are most relevant. Please examine the article Resonance (particle physics) and this one that it links: Relativistic Breit–Wigner distribution. Neither article mentions "frequency", and I think the lede to this article fails to do justice to those articles. [The treatment in nuclear physics is similar but there are differences — I think we need a new article "Resonance (nuclear physics)".] Furthermore, the field of particle physics is very fortunate in having an online library summarizing everything that is known about particle physics, each piece of information accompanied by an independent estimate of its reliability, all continuously maintained by teams of world experts. The accepted approach and terminology of the global community of particle physics to the topic of resonances is given here (which we need to cite). Do you think the lede to this article does justice to that? Layzeeboi (talk) 09:17, 16 February 2017 (UTC)

In the first place, I think you are confusing a specific use of the word resonance in particle physics, a "resonance particle", for the general concept resonance. The WP article Resonance (particle physics) should probably be renamed Resonance particle, a clearer usage in physics literature [4], [5]. Resonance particles are the subject of the PDG article you referenced. There are many examples of resonance in QM that are not "peaks" in "differential cross sections of scattering experiments... associated with subatomic particles" [6]. When a molecule of ammonia absorbs a microwave photon in an ammonia maser, the result is a "flipped" ammonia molecule, not a totally new particle. And the frequency of the microwaves is certainly relevant. Another similar example of a specialized usage of the word is Resonance (chemistry) in chemistry, which refers to delocalized electrons in molecules like benzine rings, another use in QM. The reason the word "resonance" is used for all these examples is that (as mentioned in the article Relativistic Breit–Wigner distribution you referenced) the general resonance equation for a damped harmonic oscillator from classical physics applies to all of them. That is what I think this article should emphasize. I wouldn't mind a hatnote distinguishing the usage of "resonance" for a particle, but I don't see that WP:RSs support saying that the concept of resonance is different in quantum mechanics than in classical physics.

Here are some examples of the definition of resonance from general physics textbooks and websites [7] p.425, [8], [9] p.425, [10], [11], [12]. None of them distinguish resonance in QM as different. Finally, here's the chapter on resonance in one of the most famous physics texts, the Feynman Lectures on Physics by a nuclear physicist, Richard Feynman. The purpose of the chapter is to show that resonance in all areas of physics, including QM, has the same characteristics. --Chetvorno^TALK 18:41, 16 February 2017 (UTC)

Types of resonance: Mechanical and acoustic resonance

"When sound waves strike a wall, much like in an auditorium, the sound will react to various frequency energy [emphasis mine] ...." What does that last bit even mean? The way it's worded doesn't make sense to me, so I feel a bit of grammatical editing is needed but don't know where to proceed. ("To various frequency energies"? "With various frequency energies"? And where is this energy coming from/stored?) 96.36.28.111 (talk) 13:45, 22 January 2018 (UTC) Angie

I agree, that was a pretty distorted sentence. I suspect that what he was trying to say was something like: "When sound waves strike a wall... the wall will react to various frequency components in the sound with resonant vibrations dependent on the composition and various geometrical degrees present in the wall". This seems to me to be a peripheral point at best, so I just replaced the sentence with something more relevant. --Chetvorno^TALK 02:48, 25 May 2018 (UTC)

Resonance curve formula

What is the formula to describe the magnitude of the true resonance curve as a function of exciting frequency, undamped natural frequency and Q. I want to write down the formula so I can combine it with other functions of frequency. --213.205.242.199 (talk) 01:08, 10 November 2018 (UTC)

Lead

The lead is bad. Totally obscure. DAVRONOVA.A. ✉ ⚑ 22:26, 13 December 2019 (UTC)

I agree, in addition to being obscure it has some erroneous points which I put "citation needed" tags on.--Chetvorno^TALK 21:39, 14 December 2019 (UTC)

References

I will be amending the references so that they are formatted more fully and consistently, based on WP:MOS/WP:CITESTYLE. Amitchell125 (talk) 10:40, 1 January 2021 (UTC)