Questions tagged [harmonics]

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Length of a water column executing SHM in a U-shaped Tube

I was watching the lecture 30 of Walter Lewin ( 8.01 ). Here is a link: https://youtu.be/hAYeA3Wwb4U At 29:30, when he was describing the SHM of water in a U shaped tube. Lewin says that for the ...
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Does rope in a standing wave expand and contract as it moves between being straight vs sine?

Images of standing waves often show two people using a jump rope. The shape of the rope goes from straight to waves to straight, then a sine wave the other way and then straight again as it repeats. ...
1 vote
1 answer
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Why only harmonics allowed in the Casimir effect?

My question is really a request for an intuitive explanation as to why only harmonic frequencies of photons allowed between two conduction plates. Why do the plates have to be conductive? And can real ...
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2 answers
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Is timbre a physical noumenon or a perceptual phenomenon? [closed]

I have a question relating the "timbre" of a sound, namely what is exactly and exhaustively defined by this word? Most definitions that I come across seem somewhat loose as "the color ...
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4 answers
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How can I calculate the number of nodes on a plucked string?

Given the length of the guitar string, can you predict the number of nodes that would exist on that string? My textbook says that there are an infinite number of harmonics that can be created when a ...
1 vote
2 answers
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How does one apply the phase change of $π$ on reflection at the rigid end of a string?

Consider a string, with a free end $P$ and another end $Q$ which is rigidly fixed. Now, we start oscillating the point $P$ (with $0$ initial phase difference) and a wave starts traveling(in the ...
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2 votes
4 answers
106 views

Does the standing wave equation proof require $\ell=Nλ$? [closed]

Consider two identical sources $S_1$ and $S_2$ of waves, separated by a distance $\ell$ (as shown in the figure). The sources produce waves in opposite directions(and towards each other). Now, ...
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2 votes
2 answers
189 views

Why does an antinode form at the open end of an organ pipe?

I recently learnt about reflection of waves in various media and the resultant standing waves formed. In a string which is tied at an end, the wave formed reflects with a phase difference of 180 (at ...
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0 votes
1 answer
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How to calculate the overall harmonics of a system of tubes?

Let's say there is a tube closed at one and and open from the other. The open end is connected to another tube (of smaller diameter) which is open from both ends. How can I calculate the overall ...
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2 votes
2 answers
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What exactly happens, step by step, in string harmonics?

I know that a string when plucked shows harmonics but I do not really understand how. Like, I understand resonating air column and how standing waves are formed there, but I can't seem to get the step ...
6 votes
2 answers
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Why does plucking a string produce harmonics instead of a pulse?

If I jerk a wire from the free end fixed at an end and then fix the free end, it will produce a pulse travelling back and forth between the two ends. So in a string fixed at both ends, if we pluck it ...
0 votes
1 answer
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Why is the Ocean Blue? [closed]

I'm writing an article on the physical property that binds Music and Water -- Harmonics. I understand that the blueness of ocean water is due to the three vibrational modes of water (i.e, symmetric, ...
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1 vote
1 answer
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Standing wave in a string clamped at one end

*In the case of a standing wave formed with one end clamped (fixed), there is an anti-node at the free end irrespective of the overtone. My question is why is there has to be an antinode. Is there any ...
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1 answer
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Steven Weinberg says $L$ is the fundamental EM wavelength in a cubical cavity $L^3;$ not the typically asserted $2L.$

This is from Steven Weinberg's Lectures on Quantum Mechanics, 2nd Ed., page 2: For instance, for a cubical box of width $L,$ whatever boundary condition is satisfied on one face of the box must be ...
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1 answer
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Standing waves confusion

Its just so confusing as to why the antinodes are formed from the constructive interference by superposition of the wave formed by the incident wave and the reflected wave... The phase difference is ...
2 votes
1 answer
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Which harmonic we hear from organic pipe from all possible outcome?

I have gone through about each case of standing wave in open and closed organ pipe and understand antinode and node concepts. But i am confused that if all harmonics are possible in organ pipe, then ...
1 vote
3 answers
170 views

Plucked string eigenvalues/harmonic frequencies: integer multiples (or not)

I'm trying to derive a model of a plucked string from Newton's second law. My derivation results in $$ω_n = C\cdot\sqrt{n},\, n=1,2,3\dots\text{integer}$$ I think it should be $$ω_n = C\cdot n,\, n=1,...
1 vote
2 answers
132 views

Why are there both antinodes at both ends of the tube? [duplicate]

I learned stationary/standing waves the other day. For stationary waves in open tubes, the textbook says both ends must have an antinode. Can anyone tell me why? (shown as figure) And also, when ...
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Upper limit of Schumann resonance harmonics?

This is a re-post from the Earth Science Stack Exchange which was posted two month ago. Due to the nature of the question and the SE site, it might be better to post this question here. As the Earth'...
2 votes
1 answer
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How do standing waves produce a note?

I just learned standing waves in class. And I know that fundamental frequency is the minimum frequency with which a standing can exist on a string. Then we talked about the role of standing wave in ...
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1 answer
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Question about fundamental frequencies

For a string fixed at both ends, with a fundamental frequency of 440Hz, can there be a harmonic when a wave of frequency 220Hz is sent across the string? my book says no, but I disagree; can't ...
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How to draw relation between Time Period and Amplitude of SHM?

Can we draw a relation between Time period and amplitude an object doing SHM? I came up with something but I’m not sure if it’s correct. $TA = k$, where k is a constant I came up with this just by ...
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1 answer
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Find the frequency of the first two harmonics of a vibrating string

I have a string of length $2 \;\text{m}$ and the wave velocity is $120 \;\text{m/s}$, find the frequency of the first two harmonics. My attempt, what I must do is to solve the wave equation on the ...
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0 votes
1 answer
100 views

What kind of frequency effects does a guitar body have on sound?

These are the questions I read through before asking this: Guitar string - feedback from the body Sound due to guitar Waves on a guitar string https://music.stackexchange.com/questions/5489/why-do-...
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4 votes
0 answers
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Identifying speech sounds from sound waves [duplicate]

TLDR: How do we differentiate, say, a "A" from a "O", how do we identify speech sounds? If formants are the key, how is it possible to identify it regardless of the pitch (...
0 votes
2 answers
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Harmonic wave (infinite length and duration)

I am not sure why a harmonic wave is said to have infinite length and duration. I found this image, but I am not sure I have really understood it. Here, there are three waves: the first one is a ...
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0 votes
0 answers
25 views

Saturn's moons - getting a stable harmonic model for Mimas and Encyladus

I have built a HTML/Javascript solar system model. It is working well with real time animation. https://abetz-rouse.com.au/planetarium I don't want to get into the deficiencies of my choice of ...
0 votes
1 answer
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Why can harmonics be a different note than their fundamental frequency?

I was under the impression for the longest time that when you hear a harmonic on a string, its basically a sum of different resonating frequencies, which are all INTEGER multiples of the base ...
5 votes
4 answers
241 views

Is being "stationary" also an example of a "periodic motion"?

I read an idea in mathematics about periodic functions that a constant function is also a periodic function with an undefinable period. So , suppose a body is at rest (for an observer). This means ...
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Inversion symmetry for Second Harmonic Generation

I read this question "Lack of inversion symmetry" in crystal?, but it is not quite clear to me how to clearly define the symmetry. Let me explain with a simple example. In the image below ...
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2 votes
1 answer
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Why do higher frequencies tend to have a smaller amplitude than low frequencies?

Complex waves found in nature tend to have downward sloping frequency distribution. This isn't to say the fundamental always has the highest level but the general trend is that higher overtones tend ...
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2 answers
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Why are the harmonics of a stretched string and that of an open pipe the same?

In page-376 of the NCERT physics class-11 chapter on waves (see here), the frequency relations for the harmonic of a stretched string are derived as(eq.15.42): $$ \nu_n = \frac{nv}{L}$$ Now, in page-...
3 votes
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Why are the harmonics on a string controlled by where we pluck it?

I just read this answer by rob on the question of why harmonics occur when plucking the string, in the answer I have a doubt on this point: It's worth pointing out that you have some control over ...
1 vote
2 answers
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Physics experiment with sound [duplicate]

I am doing an experiment for a school project which consists of blowing into 6 different bottles to create different notes/harmonics. Each bottle is filled with different volumes of water to create a ...
1 vote
2 answers
271 views

During sympathetic resonance in a piano, are new frequencies generated?

Sympathetic resonance in a piano is the phenomenon of one string being excited, transmitting its sound to other strings that will then start vibrating if they have common frequencies. For example C2 ...
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1 vote
3 answers
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Pendulum attached to an accelerating train

The question I have is similar to that of the Pendulum in an accelerating train problem. Where a bob is hung from the ceiling of a train that is at rest. The train then begins moving with an ...
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2 votes
1 answer
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Measuring the harmonics of a vibrating string

I have a string which is vibrating at a fixed frequency, say 1 kHz. I know it is vibrating in a purely first harmonic mode because of the (sinusoidal) drive function I am using. With a microphone I ...
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0 votes
1 answer
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Behaviour of 2 resonant tuning forks in a vacuum

The scenario is the following. Two perfectly tuned resonant tuning forks A,B are placed in the same vacuum. [ Ideally the experiment is conducted when both A&B are in free fall]. Tuning fork A is ...
0 votes
1 answer
225 views

Resonance frequency of a guitar

I have some questions for you about the resonance phenomenon in a guitar: Why resonance frequency are only full integer multiples of the natural frequency, such as 2 x, 3 x, or 4 x or 3 x, 5 x, or 7 ...
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2 answers
60 views

Waves and guitar frets

I have a problem to solve for Physics III at university and I can't seem to understand how to solve this question. I have the fundamental frequency at $440$ Hz, $L=1$ m, and $ρ=0.002$ kg/m. After ...
2 votes
1 answer
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Does electrical sawtooth wave actually produce sinusoidal oscillations at harmonic frequencies?

According to Fourier's theorem, we know that a sawtooth wave can be represented as a sum of sine waves. These sine waves we know as harmonics (in the context of sound). My understanding is that it is ...
1 vote
2 answers
445 views

What is the difference between $\omega$ and $\Omega$ in the equation $\Omega = \theta_o\omega\cos(\omega t +\delta)$?

The standard equation for any object moving in a linear simple harmonic motion (SHM) is $$x=A\sin(\omega t +\delta)$$ where $A$ is the amplitude, $\omega$ is the angular velocity. Likewise, converting ...
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Laplace transform for damped waves

In Zeidler's book on QFT, page 94 there is a definition for a Laplace transform that reads \begin{equation} (\mathcal{L} f)(\mathcal{E}) = \int_0^\infty e^{i\mathcal{E}t/\hbar}f(t) dt, \end{equation} ...
27 votes
7 answers
7k views

Why do higher harmonics have a lower amplitude than the fundamental frequency?

When we pluck a string, it vibrates in all possible modes of vibrations. The lowest frequency possible is the fundamental frequency and it is the most significant part of sound. But why do the ...
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4 votes
2 answers
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Why are there no even harmonics in a closed pipe?

I have seen a diagram on sites such as hyperphysics.com that show that there is a missing bit every time so that it makes every harmonic odd. I was hoping I could get a more intuitive explanation. We ...
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2 votes
3 answers
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Relation between frequencies of different harmonies

I know the relation between frequencies of different harmonies is $$ f_n = n\times f_1 $$ but I'm heving trouble to develope the equation which proves this equality. can anyone please give me a lead ...
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1 answer
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How do cavity resonators differ from tubes of uniform width?

I read that wine bottle produces sound when u blow sideways onto its rim because some frequencies of the white noise produced in your mouth gets amplified when they match the natural frequency of the ...
1 vote
1 answer
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Finding the conditions for a resonant (unique single mode) state in the wave equation

If we have a string of length $L$ in constant tension $T$ and we oscillate one of the extremes at the rate $\sin{\frac{\pi nc t}{L}}$, we observe in a lab that single harmonics are produced. I want to ...
2 votes
1 answer
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What is the relation between the fundamental frequency and a harmonic?

I am currently busy with a physics report about determining the speed of sound in air. In order to do this, I was told to use a tube that can extend or shorten in order to find the different harmonics ...
1 vote
1 answer
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What causes this high frequency "noise" in HHG spectra?

Looking at high harmonic spectra, one can often see that peaks corresponding to higher harmonics look more and more noisy and seem to be drowned out by the noise. For example, one such spectrum is ...