New answers tagged waves
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Can sound waves be reflected/absorbed using a microwave-oven type mesh?
Acoustic waves are mechanical, not electromagnetic. Acoustic waves propagate as standing waves of pressure through a transfer medium. Both wave types can travel radially in 3 dimensions. The acoustic ...
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Why is the ground mode the only excited mode in acoustics?
It is not surprising that researchers would have neglected to analyze the contributions of higher order harmonics. Generally, in most physical systems higher order modes contribute progressively less ...
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Is there a publication on the speed of sound assuming heat conduction is taken into account?
Mechanical Radiation by Robert Lindsay discusses the effects of heat flow on sound waves in Section 9.12. The discussion is primarily couched in terms of attenuation, but as a side result of this ...
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Can human ear hear 4 Hz frequency, if I tap my hand 4 times per second on table?
This video of Euler's disk provides a useful example.
Listen to the sounds. Around 0:30, you can hear a noise in 4Hz or so. You will notice that it's clearly "pulsing" - you can tell the ...
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How is energy distributed over the normal modes?
(1): if you solve the linear eigenvalue system of normal modes, you can construct the most general solution as $f \propto \sum_j c_j o_j(t) d_j(x)$ where $o_j(t)$ is the time dependence of mode $j$ ...
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The physics behind the circle / spiral of fifths
There are physiological reasons why the octave (2:1 ratio) and the perfect fifth (3:2 ratio) sound particularly harmonious to the human ear. The perfect fourth (4:3 ratio) also sounds harmonious, and ...
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Is sound really adiabatic because it is a fast process?
Sound propagation is indeed better modeled as an isothermal process at higher frequencies, for exactly the reason you note: With a shorter wavelength, the hotter and colder regions are closer and more ...
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How are neutral conductors neutral even though they microscopically aren't?
The equation
$$
\nabla \cdot \mathbf E = 0
$$
is from macroscopic EM theory, where material medium is a continuous region of space with different behaviour and relation between the fields $\mathbf E,\...
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How are neutral conductors neutral even though they microscopically aren't?
You are asking a good question, and it is sad that there are people downvoting.
The meaning of the Maxwell's equations in materials is actually an extremely delicate subject. To get the zero, we ...
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Can human ear hear 4 Hz frequency, if I tap my hand 4 times per second on table?
In the discussion under Marco Ocram's answer there was a discussion about whether the frequency that a sound is repeated at is reflected as a component in the frequency spectra. I was asserting that ...
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Can human ear hear 4 Hz frequency, if I tap my hand 4 times per second on table?
Strictly considering whether the ear is hearing a 4 Hz wave, the answer is definitely no. Your ear doesn't transduce (pure) 4 Hz waves, and as the other answers mention, there isn't even much energy ...
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Can human ear hear 4 Hz frequency, if I tap my hand 4 times per second on table?
The sound that the clap itself creates has a higher frequecy than 20 Hz, since it is audible.
The number of sounds in a given period can also be expressed as a frequency, but this should be seen as ...
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Can human ear hear 4 Hz frequency, if I tap my hand 4 times per second on table?
You are not producing a 4 Hz wave—you are producing four sets of sounds, each with a spread of audible frequencies. If you had a 4 Hz sinusoidal wave you would not hear it.
If you tap a drum, for ...
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Working principle of Shack-Hartmann Wavefront Sensor
The displacement of the wavefront is a linear distance, often measured in waves or microns, and usually described as W(x,y). If measured in waves, you can convert that to a linear distance if you ...
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What is the relevant phenomenon behind Undulatus/Radiatus cloud formations?
There are a variety of cloud wave patterns, including radiatus, undulatus, and gravity wave clouds. Their causes are not mysterious, but fluid mechanics is rarely simple. When air rises and falls in ...
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Is sound essentially motion?
All sound is motion, but not all motion is sound.
The first topic to discuss would be oscillation. In theory, one can use the Fourier transform to decompose any motion into the sum of oscillating ...
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Physical interpretation of source term in wave equations
Perhaps clarity is enhanced by viewing this source term as an excitation of a wave. This term represents the process of imparting energy to a medium or system in a manner that generates a disturbance ...
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Could the double slit experiment demonstrate not that particles behave like waves, but that together particles behave as a wave?
Yes they can and do. Sound waves are caused by the collective actions of atoms. Individual atoms vibrate back and forth and don't really go anywhere. But each is well approximated by having a definite ...
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Could the double slit experiment demonstrate not that particles behave like waves, but that together particles behave as a wave?
One way to test your idea is to send electrons through the double-slit one at a time. You could send a single electron through once every month, or once every decade. However long we wait between ...
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Can a standing wave indistinguishable from a travelling wave for a stationary observer?
Is your stationary observer only able to see the amplitude of the wave at a single point? If so, he will see the amplitude at that point oscillate up and down with either wave. Based on his view of ...
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Is it not possible for true standing waves to appear in nature?
Those three conditions are only needed exactly for a standing wave of infinite duration. Since the universe has a finite duration obviously such a wave is trivially not possible.
However, for standing ...
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Frequency of Sound Waves
Low-frequencies sound waves travel further than high-frequency sound waves so assuming that the original sound is not a pure sine wave but is a mix of frequencies (or is a fundamental frequency with ...
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Phase Angle: AC Circuit
You can do it the way you describe it, it's just not the convention.
It would not be unreasonable to write the equation as $y=\
sin(\omega (t + \tau))$. In this case, I choose $\tau$ rather than $\...
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Phase Angle: AC Circuit
Red graph - crosses the time axis at $t=-0.43\,\rm s$
$\omega = \frac {2\pi}{3}$ radians per second, thus a time of $0.43\,\rm s$ represents an angle $\phi = \frac {2\pi}{3} \times 0.43=0.9\,\rm ...
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Phase Angle: AC Circuit
What am I missing?
You are missing the units. The term $\omega t$ is an angle so $\phi$ must also be an angle in order to add $\omega t+ \phi$.
Your expression $\omega(t+\phi)$ is dimensionally ...
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What is an electromagnetic wave exactly?
Electric force and magnetic force are the actual base phenomena. Charges attract or repel each other based on their movement and/or distance, and we model this as a force. The field is a convenient ...
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What is an electromagnetic wave exactly?
Let's start with a Reltivitistic Classical Theory first, the theory of electromagnetic fields.
One of the most important contributions to physics that has shaped the way we think of continuity and ...
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Is the argument of the $\sin$ function for a monochromatic plane wave dimensionless?
There is something you're missing. You're missing that in this formula, $\nu$ is the spatial frequency (or wavenumber), not the temporal frequency. It has units of $\rm{length}^{-1}$.
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What is an electromagnetic wave exactly?
In the context of classical electromagnetism, there is no physical entity that directly connects the electric field at one point to its nearby points, analogous to how a string connects adjacent ...
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What is an electromagnetic wave exactly?
In case of electromagnetic waves, the electric field values oscillate with time.
A measurable EM wave consists of a decreasing and increasing number of polarised photons and is induced by a wave ...
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What is an electromagnetic wave exactly?
If the base on earth receives a signal from a device on Mars for example, we can be puzzled by how the wave could propagate in the vacuum from one point to another nearby and so on until arrives here.
...
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What is an electromagnetic wave exactly?
When Maxwell developed the theory of electromagnetism, he and everyone else assumed that there was some kind of material substance that actually vibrated, and those vibrations were the electromagnetic ...
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What is an electromagnetic wave exactly?
But is there anything physical that connects the electric field at a point to that at its nearby points (just like we had for strings) ?
Yes, the field itself is spatially connected. In Maxwell’s ...
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What is an electromagnetic wave exactly?
I don't know if I got the full question, but I think the main point of your question is "But is there anything physical that connects the electric field at a point to that at its nearby points&...
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Does a linearly accelerating spherically symmetric body emit gravitational waves
According to Birkhoff's Theorem, any spherically symmetric body will not emit gravitational waves. <…> But now imagine, we have a spherically symmetric body that is linearly accelerating through ...
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Why the consecutive spherical wavefronts produced by a rest point source are not equidistant?
Both of your are right, because you and ChatGPT have different ideas of what the term "equidistant wavefront" means. For you, the point source does "doot doot doot" and the doots ...
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Why the consecutive spherical wavefronts produced by a rest point source are not equidistant?
"As a result, the distance between consecutive spherical wavefronts increases as they move away from the source." This is a non sequitur; it doesn't follow from the previous sentence. Nor is ...
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Can two normal 1D waves form a wave packet?
The resulting wave will look like that pictured below, and I agree with mmesser314's answer that it would be unusual to call such a wave a "wave packet". That said, it does make sense to ...
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Is there a Doppler effect on the surface of an expanding balloon?
Suppose the mechanical properties of the balloon were not affected by being stretched. That is, suppose you took a balloon and stretched it $10$%. The speed of waves is the same as an unstretched ...
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Can two normal 1D waves form a wave packet?
It sounds the problem is misstated a bit. A wave packet is typically a single (perhaps complicated) pulse, where a wave is periodic.
The sum of two periodic waves is periodic. So perhaps it should ...
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Does a linearly accelerating spherically symmetric body emit gravitational waves
Yes, it would produce waves. Its position and hence its mass distribution relative to a fixed point changes over time, so the quadrupole moment is changing. Since it is accelerating, the second ...
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Wavelength of a mechanical wave in different media
The velocity v in wavelength equation can be calculated as a square root of elastic modulus devided by material density. Velocity obtained from this equation is called transversal speed of sound and ...
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Phase Difference between Electric and Magnetic Field in EM waves?
Yes. The relationship between $E_i$ and $H_j$ is given by the impedance $Z = \sqrt{\epsilon/\mu}.$ It can have an imaginary part, introducing a phase $\arg(Z)$. For example in the Debye model, you ...
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How do you interpret the statement that a wave is a travelling wave if $f(x,t) = f(x \pm vt)$?
$$
f(x,t) = f(x \pm vt)
$$
but this doesn't really make any mathematical sense to me. How can you substitute in a single argument back into a function that takes multiple arguments?
You are ...
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How do you interpret the statement that a wave is a travelling wave if $f(x,t) = f(x \pm vt)$?
Maybe this becomes more clear if parameters are used: If in $f(x-vt)$ t is set to a constant t1 and treated as a parameter then you have a function of x, $f(x)$. This function can be plotted on a ...
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Acoustic wave incident to pipe wall
Introduction
At every interface (change of medium, or better density) there is some reflection. This has to do with the change in the impedance “seen” by the impinging wave.
It is safe to assume that ...
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How do you interpret the statement that a wave is a travelling wave if $f(x,t) = f(x \pm vt)$?
Roughly speaking the statement says that travelling waves along the real axis, though in principle functions of $x$
and $t$ separately, they are actually functions of the combinations $x-vt$ or $x+...
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How do you interpret the statement that a wave is a travelling wave if $f(x,t) = f(x \pm vt)$?
In this context, to me this is shorthand for, the function $f(x,t)$ of position $x$ and time $t$ is a (linear) combination of a function of $x+vt$ and a function of $x-vt$.
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How do you calculate phase from sin wave equation?
For the equation you have assumed, the phase shifts by time but stays the same. So you could simply ignore the $\omega t$ for the sake of simplicity. Therefore, to be sure of the phase, you could ...
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How do you calculate phase from sin wave equation?
Well, the equation you present is not the wave equation but one of the many possible solutions to it.
The phase $\phi$ refers to the value of the solution at $t = 0$ for a distance from the source $x =...
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