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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What happens to the energy when waves perfectly cancel each other?
What happens to the energy when waves perfectly cancel each other (destructive interference)? It appears that the energy "disappear" but the law of conservation of energy states that it can't be ...
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4answers
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Why is the angle of the wake of a duck constant?
Why is the angle of a wake of a duck constant? And why are some conditions on the water depth necessary?
I realize that this question turns up in google searches, but I did not see a good discussion. ...
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2answers
475 views
Are gravitational waves longitudinal or transverse?
Waves are generally classified as either transverse or longitudinal depending on the they way the propagated quantity is oriented with respect to the direction of propagation. Then what is a ...
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3answers
734 views
Amplitude of an electromagnetic wave containing a single photon
Given a light pulse in vacuum containing a single photon with an energy $E=h\nu$, what is the peak value of the electric / magnetic field?
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5answers
4k views
Why do tsunami waves begin with the water flowing away from shore?
A sign of a tsunami is that the water rushes away from the shore, then comes back to higher levels. It seems that waves should be both + and - polarized and that some tsunamis should go in the ...
13
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7answers
1k views
What is a general definition of impedance?
Impedance is a concept that shows up in any area of physics concerning waves. In transmission lines, impedance is the ratio of voltage to current. In optics, index of refraction plays a role similar ...
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3answers
233 views
Validity of naively computing the de Broglie wavelength of a macroscopic object
Many introductory quantum mechanics textbooks include simple exercises on computing the de Broglie wavelength of macroscopic objects, often contrasting the results with that of a proton, etc.
For ...
9
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2answers
332 views
Circular polarization of variable-frequency light by 3D cinema glasses
A dominant method to obtain 3D images in the cinemas seems to be circular polarization. Separate pictures are projected with (alternating) circular polarization filters and passive glasses of the ...
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5answers
509 views
Superposition of electromagnetic waves
The superposition of two waves is given by
$$\sin(\omega_1 t)+\sin(\omega_2 t)=2\cos\left(\frac{\omega_1-\omega_2}{2}t\right)\sin\left(\frac{\omega_1+\omega_2}{2}t\right).$$
For sound waves, this ...
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1answer
96 views
Wave Physics - can a dynamic waveform be constrained to a specific geometry by signal processing alone?
Suppose that you have a signal source, a set of point-transducers, and a handful of moderately powerful DSPs. Is it possible to construct an arrangement of the transducers such that the original ...
8
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2answers
902 views
Popular depictions of electromagnetic wave: is there an error?
Here are some depictions of electromagnetic wave, similar to the depictions in other places:
Isn't there an error? It is logical to presume that the electric field should have maximum when ...
8
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4answers
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Are water waves (i.e. on the surface of the ocean) longitudinal or transverse?
I'm convinced that water waves for example:
are a combination of longitudinal and transverse. Any references or proofs of this or otherwise?
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3answers
420 views
Why does energy in earthquake waves seem to go up with the three halves power?
My question might be based on a false premise, so here's why I asked. If you look up the meaning of the moment magnitude scale for measuring earthquake size, the articles usually say that each ...
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2answers
181 views
Shape of wall's deformation wave caused by baseball's impact
Clicking through this year's top sports pictures, I stumbled upon this one. I was wondering about the shape the baseball is leaving on the wall.
What phenomenon causes this peculiar shape? Why is ...
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3answers
2k views
Waves in water always circular
I have had a question since childhood. Why do we always get circular waves (ripples) in water even when we throw irregularly shaped object in it?
7
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2answers
222 views
Can light waves cause beats?
My question is pretty brief. When two sound waves of nearly same frequencies interfere, we get beats.
But, I have not observed something like that happening in the case of light. In fact, most of the ...
7
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2answers
231 views
Is there a good chance that gravitational waves will be detected in the next years?
Is there a good chance that gravitational waves will be detected in the next years?
Theoretical estimates on the size of the effect and the sensitivity of the newest detectors should permit a ...
7
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5answers
839 views
Why don't waves erase out each other when looking onto a wall?
If I stand exactly in front of a colorful wall, I imagine the light waves they emit, and they receive should randomly double or erase out each other.
So as a result, I imagine I should see a weird ...
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2answers
139 views
Does light have timbre?
Timbre is a property associated with the shape of a sound wave, that is, the coefficients of the discrete Fourier transform of the corresponding signal. This is why a violin and a piano can each play ...
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3answers
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Phase shift of 180 degrees on reflection from optically denser medium
Can anyone please provide an intuitive explanation of why phase shift of 180 degrees occurs in the Electric Field of a EM wave,when reflected from an optically denser medium?
I tried searching for it ...
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3answers
811 views
Why is it necessary for an object to have a bigger size than the wavelength of light in order for us to see it?
I keep hearing this rule that an object must have a bigger size than the wavelength of light in order for us to see it, and though I don't have any professional relationship with physics, I want to ...
7
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0answers
65 views
Slinky reverb: the origin of the iconic Star Wars blaster sound
This is a fun problem that I came across recently, which I'm posting here for your delectation. We all love a good slinky: they can be used for all sorts of fun demos in physics. One example is the ...
7
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2answers
125 views
How to reproduce highway vibration?
I would like to test my hardware under vibration that can appear on a highway gantry.
If someone has a model of such vibration. i.e period and amplitude.
In my lab I have a motor that can be ...
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6answers
562 views
What is the meaning of the word “particle” in particle physics?
I want to use Matt Strassler's definition of the word "particle" as a specific example:
Matt Strassler writes:
(1) "...all the elementary “particles” (i.e. quanta) of nature are
quanta of waves ...
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2answers
161 views
Multiple channels of information in single electromagnetic wave?
I'm trying to understand how can multiple radio stations transmit information just by transmitting using different frequency. The way I understand it all those different frequency waves add up to a ...
6
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3answers
274 views
Controllable faster-than-light phase velocity
This is not another question about faster-than-light travel or superluminal communication. I totally appreciate the speed limit capped by physical laws (or theories.)
Just curious, since there is no ...
6
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1answer
97 views
How to model the form of a surface water wave?
Normal surface water waves, as generated by wind, do not have sine form but wave peak is higher and shorter than wave trough with different wave steepness. What parameters characterize such a surface ...
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3answers
196 views
Intuitive explanation for the de Broglie / Planck relations
A friend asked me to explain "why" a particle's energy is proportional to it's frequency, i.e: $$E=h\nu$$
The reason this result is so un-intuitive, is that in the macroscopic world, A wave's energy ...
6
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1answer
259 views
How to simulate a crashing wave?
I'd like to create a very rough animation of a wave crashing on a beach. I'm guessing it would have to be a particle simulator, where you code in the forces between the particles and then integrate ...
6
votes
2answers
101 views
How does one explain this pattern generated by earthquake waving driving a pendulum?
How to explain this pattern generated by earthquake wave driving a pendulum? Specially, there are three groups of curves that look categorically different:
1) The group of curves outside the ...
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2answers
153 views
How do the LASERs in LIGO realize that space has expanded as a gravitational wave passes by?
I read an article on LIGO, and I heard it mentioned that it is a nontrivial argument to say that the effect can be measured by interferometry. What happens to space as the wave passes? Does the light ...
6
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2answers
92 views
Relaxation time for deviations from spherical shape of a black hole's event horizon (and waves)
A different question about truly spherical objects in nature (Do spheres exist in nature?) made me think of a lecture I had been at where, as I recall, it was mentioned that the most perfectly ...
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1answer
303 views
The role of metric in the Wave Equation
The wave equation is often written in the form
$$(\partial^2_t-\Delta)u=0,$$
involving the Laplace-Beltrami operator $\Delta$. However, the Laplace-Beltrami operator $\Delta$ is defined only in the ...
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8answers
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Doppler's effect use
While i was in high-school i learn't the Doppler's Effect which if i remember correctly is:
The Apparent change in the frequency of sound caused due the relative motion between the sound and the ...
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3answers
374 views
What is the mass of a wave?
The slide called "QUANTA" here says that "One Quantum has a definite mass" and the picture shows a wave. So, What is meant by the mass of a wave?
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3answers
183 views
Is a soundproofed wall really only as strong as its weakest area?
I've seen a few questions about sound waves and sound travel here on Physics SE, so I'm hoping this question is a good fit for this site.
During my internet research on soundproofing, I've come ...
5
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2answers
268 views
How does infrared light 'erase' phosphorescence on zinc sulfide?
I found some sheets of zinc sulfide in my basement that phosphoresce green for up to 24 hours or so after exposure to bright light in the violet range or shorter. One of the first things I tried was ...
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2answers
238 views
What is a wave?
I was watching an outtake of Prof. Brian Cox talking to a tv producer about "gravity waves". Their discussion got a bit side-tracked, because the non-scientist didn't seem to understand what a wave ...
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2answers
337 views
What are the normal modes of a vertical rope?
Closely related to this question on traveling waves on a hanging rope, I would also like to know what the normal modes are on a rope that hangs vertically, fixed at both ends.
Tension in the rope ...
5
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2answers
146 views
De Broglie wavelength, frequency and velocity - interpretation
Two fundamental equations regarding wave-particle duality are:
$$ \lambda = \frac{h}{p},
\\
\nu = E/h .$$
We talk about de Broglie wavelength, is it meaningful to talk about de Broglie frequency ...
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5answers
970 views
How to Make RF Waves Visible
I understand RF (Radio Frequency) Waves are electromagnetic waves and a mode of communication for wireless technologies, such as cordless phones, radar, ham radio, GPS, and television broadcasts. Most ...
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3answers
2k views
What happens to sound waves?
I apologize if this is a naive question, but I never really learned about this. I'm curious as to what happens to sound waves after they are "used"? For example, if I say something to you verbally, ...
5
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2answers
83 views
In terms of the Doppler effect, what happens when the source is moving faster than the wave?
I'm just trying to understand this problem from a qualitative perspective. The Doppler effect is commonly explained in terms of how a siren sounds higher in pitch as it is approaching a particular ...
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2answers
1k views
Reflection of transverse and longitudinal waves
Why is it that when a transverse wave is reflected from a 'rigid' surface, it undergoes a phase change of $\pi$ radians, whereas when a longitudinal wave is reflected from a rigid surface, it does not ...
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2answers
108 views
Wave with mass transport?
I don't think this question has been asked on this forum before (at least I didn't find it).
In the case of a tsunami, an earthquake generates a wave which will travel with the sea/ocean as the ...
5
votes
5answers
781 views
Why aren't there compression waves in electromagnetic fields?
I just started learning about optics, and in the book I'm reading they explain how the electrical field caused by a single charged particle could be described by a series of field lines, and compare ...
5
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1answer
168 views
Resonance modes of a cubic box of water which we shake
I don't know hydrodynamics, but I wonder how one would compute resonance modes of a cubic box of water which we shake. I believe the waves would directly depend on the height of water and the width ...
5
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1answer
504 views
Why and how is sound produced when two objects hit each other?
When two objects collide and undergo a partially inelastic collision (so every one we experience in every-day life), they rebound to a certain degree, but kinetic energy is not conserved. Thus, the ...
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3answers
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Why do bass tones travel through walls?
I was in the shower while my roommate was listening to music and got to thinking about the fact that I could only hear the bass and lower drums through the walls. Why is this? The two possibilities I ...
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1answer
130 views
Why does the echo for soundwaves hitting a vacuum come back out of phase? [duplicate]
Possible Duplicate:
Phase shift of 180 degrees on reflection from optically denser medium
I've read in a physics book for musicians that, when a soundwave hits a near-solid object, it ...
