Waves are disturbances that propagate throush space and time. Classically, they travelled through a medium, disturbing the particles but not changing their mean position. Electromagnetic waves/particle-waves need no medium; they are disturbances in their respective fields.
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Can we compute the magnitude of the stress caused by sound waves on a wall?
As a follow up to this question, Could we really compute the magnitude of the stress caused by sound waves on a wall? If so, How do we do that?
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79 views
After quantization of electron vibrations, do we need electrons anyway?
The title question is not ment in a general context, but one in which goes to the plasmon theory.
In that case, how is are the statistics (boson vs. fermions) of plasmons determined?
And is there an ...
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0answers
172 views
How to predict sea waves length/height?
I would like to know which are the best methods used to predict sea waves characteristics (particularly predict length/height given water depth and wind speed) and how are they used. My major is ...
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6answers
768 views
What is the meaning of phase difference?
What do you mean by phase of a wave? And phase difference? Waves have always confused me as it's too difficult to visualize them. I am no good at waves mechanics, so if anyone could explain in simpler ...
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3answers
388 views
Is it correct to say that electromagnetic waves does not require a medium?
I can conceive of a particle existing in empty spacetime, but not a wave. A wave appears to me at least, to insist upon a medium for its very definition.
I understand that the 19C physicists ...
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2answers
352 views
Through a lens, which light beam reaches the screen first?
Imagine three light beams are "sent" to a lens simultaneously, they start at the same position but move towards the lens at different angles. The first light beam passes the lens at its edge, the ...
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2answers
60 views
Pressure in waves on a string
We know that when we speak sound waves are created. The air particles compress and rarefy and pressure is more at the nodes and less at anti-nodes. But can we say the same thing about waves on a ...
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1answer
454 views
How radio waves penetrate through buildings?
For example how radio signals of a base transceiver station (BTS) penetrate through buildings?
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2answers
3k views
Sinusoidal Wave Displacement Function
I am learning about waves (intro course) and as I was studying Wave Functions, I got a little confused.
The book claims that the wave function of a sinusoidal wave moving in the +x direction is as ...
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2answers
799 views
Why does Davisson-Germer experiment confirm electron's wave-particle duality?
First I apologize if my question is trivial and for my poor English.
I was wondering why my teacher states that "electron's wave-particle duality is verified if we observe diffraction of the electron ...
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1answer
139 views
Spring oscillations and waves
Consider a block of mass $m$ attached to a spring. Let it oscillate at a frequency $f$. Now each part of the spring is in SHM. so this means a wave is propagating through this spring.bCan this wave be ...
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3answers
2k views
How do you find the velocity function of a mechanical wave?
With the form $y(x,t)=A\sin(kx-\omega t+\phi_0)$, there are two variables, How do I find the velocity? I don't know I can apply derivative with two variables.
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2answers
217 views
Creation of the Electromagnetic Spectrum [closed]
After seeing this image:
http://mynasadata.larc.nasa.gov/images/EM_Spectrum3-new.jpg
And reading this:
"The long wavelength limit is the size of the universe itself, while it is thought that the ...
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2answers
152 views
Standing Waves Energy transfer
And In a standing wave , how does energy travel past a node in a string ?
It should just get reflected . Assume the case of first overtone and you strike the string at a place . How will energy ...
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4answers
157 views
wave-particle duality
I have been trying to understand "wave-particle duality" and other cases related to it. I am currently a college level student. I have few question which I am not getting answers clearly.
In double ...
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2answers
449 views
How to get “complex exponential” form of wave equation out of “sinusoidal form”?
I am a novice on QM and until now i have allways been using sinusoidal form of wave equation:
$$A = A_0 \sin(kx - \omega t)$$
Well in QM everyone uses complex exponential form of wave equation:
$$A ...
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2answers
926 views
Frequency of the sound when blowing in a bottle
I'm sure you have tried sometime to make a sound by blowing in an empty bottle. Of course, the tone/frequency of the sound modifies if the bottle changes its shape, volume, etc.
I am interested in ...
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2answers
212 views
matter wave and wave function
Is there any mathematical relationship between matter wave (or de Broglie wave) and wave function?
Also, does each type of particle (e.g. photon, electron, positron etc.) have its own unique wave ...
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2answers
78 views
Mechanical Waves
In the book Young and Freedman 13th edition, the wave equation is $y(x, t) = A\,\text{cos}(kx-wt)$ The problem is, I find it hard to console with the fact that $y(x, t) = A\,\text{sin}(wt-kx)$. ...
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3answers
90 views
How to design an experiment that shows that a rectangular pulse can be expressed as a series of infinite sinusoids?
Is it possible to design a physical experiment that shows that a time limited signal, such as a rectangular pulse is composed of infinite continuous sine/cosine waves?
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2answers
139 views
Pulsed Spherical Wave
Can somebody help show me how a pulsed spherical wave has a wavefunction of the form U(r,t) = (1/r)a(t-r/c), where a(t) is an arbitrary function, r is the radius of the spherical wave, t is time, and ...
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2answers
74 views
What is difference between the miltary radar in 1940's from commercial antenna that is for the use of TV
What is difference between the miltary radar in 1940's from commercial antenna that is for the use of TV?
I have read article from some of the WW2 history website that call the German radar the ...
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2answers
214 views
How does gravitation propagate along curved spacetime?
In this wikipedia article it is described how a beam of light, with its locally constant speed, can travel "faster than light". That is to say it travels a distance, which, from a special relativistic ...
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1answer
1k views
Explain the direction of waves on sea shore
Why do waves on the sea shore move towards the shore even when the tide is going out?
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1answer
89 views
Reflected and refracted wave sphased
When we derive refraction and reflection laws for a generical plane wave on a surface, we say that reflected and refracted must be in phase with the incident wave. Why a medium cannot do a sphased ...
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1answer
59 views
Will changing amplitude change the frequency?
Will changing the amplitude change the frequency of a wave, or is it possible for a specific frequency (50 Hz. for example) to generate from shifting amplitude patterns?
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1answer
123 views
Cylindrical wave
I know that a wave dependent of the radius (cylindrical symmetry), has a good a approximations as $$u(r,t)=\frac{a}{\sqrt{r}}[f(x-vt)+f(x+vt)]$$ when $r$ is big. I would like to know how to deduce ...
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2answers
192 views
What is light, and how can it travel in a vacuum forever in all directions at once without a medium?
I know there are many questions that are similar (maybe identical?). I am not a physicist nor a student - I am just interested in physics and have been watching many physics channels on youtube ...
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1answer
90 views
Why are clouds wavy?
Say you're in an ascending airplane as your 10 year-old son asks you: "Dad, why are these clouds wavy?" Now, say you know a little about gravity waves and the formation of wavy clouds(Maybe I should ...
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2answers
538 views
What does the velocity of a wave mean?
I know that the velocity of a wave is given by $v=\lambda f$ but what does this velocity represent in the physical sense. For instance, if I am told a car moves at a velocity of 5 $m/s$ I know that ...
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2answers
180 views
Particles vs Waves
As I remember long ago, in my physics classes, I always had a great trouble understanding the concept of waves. Our professor used to explain, as if everything in this world is made up of waves.
...
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1answer
131 views
How to prove equations for energy of a wave
In my textbook, it says that the energy (I) of a wave, determined by the power of a wave (P) divided by area (A), is determined by the following formula:
$$I = \frac{1}{2}\rho v\omega^2A^2 = 2\pi^2 ...
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2answers
442 views
Questions regarding standing waves
I have two questions regarding mechanical waves.
1) We know that standing waves are created when any wave traveling along the medium will reflect back when they reach the end. But in an open organ ...
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2answers
262 views
Standing wave and energy flux
Here is a problem I have been asked that I do not know the answer. Consider two ideal wave generators (it can be sound generator or whatever) separated by a distance L and facing each other. At t=0 ...
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2answers
595 views
Producing photons with same frequency, different amplitude wave
I don't understand how two photons of the same frequency can have different amplitudes, neither how to produce them.
I know that classically the square of the amplitude is proportional to the energy, ...
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2answers
324 views
Does a cycle (in Simple Harmonic Motion) have to equal 2π?
So, I search for the definition of cycle and I get this in Wikipedia:
A turn is a unit of angle measurement equal to 360° or 2π radians (or ...). A turn is also referred to as a revolution or ...
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1answer
247 views
Angular frequency. Wrong interpretation at Wikipedia?
This and this articles mention that the angular frequency is:
number of oscillations per unit of time
But this doesn't seem to be correct since the angular ...
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1answer
91 views
Waves and information
I'm looking to transfer very simple information using audio waves. One of the approaches I'm looking into is using different frequencies. For example, "command 1" will be transmitted using 500Hz wave, ...
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1answer
137 views
Time evolution of wave spectrum
A useful way of thinking (not only) oceanic waves is to consider them as a superimposition of linear modes: the elevation η of the sea surface is given by:
1: $\eta({\bf x}, t) = ...
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2answers
153 views
EM irradiament and multipoles
Why in the irradiament mulipoles of Lienard-Wiechert's potential we say that electric quadrupole give a contribute of the same order of the magnetic dipole? How can we see it from their equations? And ...
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2answers
47 views
Refraction of light and frequency dependence
Why do higher frequency waves refract more, both ocean waves and light waves? Also why is energy stored in the frequency as opposed to the wavelength.
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1answer
50 views
How large of a solar sail would be needed to travel to mars in under a year?
I'm attempting to approach this using the identity
$$F/A = I/c$$
I can solve for Area easily enough
$$A = F(c/I)$$
and I know the distance $d$ is
$$d=1/2(at^2)$$
But I'm having difficulty trying to ...
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1answer
32 views
Why frequency and tension doesn't change in the two medium?
I am reading a book about wave mechanics. There are two different cord (one light and one heavy) connected together, one person waving the lighter one, the wave transverse to the right from the ...
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3answers
109 views
Waveguides (in the ocean?)
The speed of sound in the ocean is given by
$$c_s(\theta,z) = 1450 + 4.6\theta - 0.055\theta^2 + 0.016z$$
$\theta$ is the temperature in degrees celcius, and $z$ is the depth. In a simplified model, ...
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1answer
57 views
Power radiated by the sun at different locations
I am wondering can someone help to solve second part which extends first part;
The power radiated by the sun is ${3.9*10^{26}}_{watt}$. The earth orbits the sun in a nearly circular orbit of radius ...
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1answer
233 views
Wave propagation in an incompressible flow
Incompressible approximation of fluid flow is usually known to be lame in modeling the propagation of any disturbance in it, predicting a speed equal to infinity for the propagation of the ...
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1answer
75 views
Acoustic wave equation for a closed sphere
I am looking to model the nodal surfaces in a resonating closed sphere. The sound source is external. What sort of wave equation will reveal the spherical harmonics depending on the frequency, speed ...
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1answer
86 views
Eikonal approximation for wave optics. Why follow the unit vector parallel to the Pointing vector?
The description of the passage from wave optics to geometrical optics claims that light rays are the integral curves of a certain vector field (the Pointing vector direction, normalized to 1). Here ...
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1answer
443 views
Deriving group velocity
At the introduction to quantum mechanic phase $v_p$ and group $v_g$ velocities are often presented. I know how to derive $v_p$ and get equation:
$$
\scriptsize
v_p=\frac{\omega}{k}
$$
What i dont ...
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1answer
140 views
Refraction seismology - travel time for wave
I am taking an introductory class in seismology, but have some difficulties understanding the logic behind the formula used to calculate the time it takes for a refracted wave to return to the surface ...
