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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29 views

How to represent a multiple in the frequency domain

So, in my previous question Where does this formula for prediction of a multiple wave come from?, I get that using this picture: we have so far written the time it takes for a multiple to travel ...
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2answers
87 views

Can sound be propagated without initial mechanical interference?

I have researched up a little on sound, and it seems that sound is a mechanical wave that propagates through the air as energy, and that is how we hear it through our ears. Depending on the medium's ...
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5answers
240 views

Is it possible for a sound to be louder as you move away from it?

I was asked a puzzling question/thought experiment: Given the source of a sound in a wide open field so acoustics do not play a role, is it possible for a sound to be louder as you move away from it. ...
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1answer
78 views

Period of Double Slit Experiment

What is the period of the pattern from the double slit experiment? It varies along the pattern right? Namely I'm confused because when considering two point sources (See: Period of Interference ...
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1answer
153 views

How/Why does voltage reflect?

I'm trying to understand antenna theory again, and I'm again stumped by the concept of VSW (voltage standing waves). I understand standing waves, I remember these from a physics clases, however I do ...
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1answer
96 views

Does sound cancel itself out?

If there are two 10 x 2 x 1 foot rectangles in space and they are lined up so if they hit each other there will be no spots that are not hit in the front of the rectangle. Then they are pushed forward ...
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3answers
113 views

What is fundamental difference between wave and its 180 flip phase?

I'm studying property of sound wave and I was wondering what is difference between two waves (one is original and one is 180 flip phase of original) ? Amplitude and frequency remains same and also ...
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1answer
65 views

How does the light waves make up to my eye?

I was thinking about a situation were there is a group of people in a room. While all those people are observing something(none of them are blind) the light ways need to reach their respective eyes. ...
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1answer
65 views

Initialize a traveling wave in a 1D gas?

I am trying to initialize a traveling wave for a 1d simulation as one can see from the attached figure. Such that it will be traveling to the right. However, I cannot initialize the right velocity ...
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3answers
128 views

Classical Wave Equation - Approximations

I don't understand the derivation of the wave equation given below - $$T \sin (\theta _1) - T \sin (\theta ) = T\tan (\theta _1 )-T\tan (\theta ) = T \left. \left(\frac{\partial f}{\partial z} ...
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1answer
72 views

Why are waves, the means, of information transfer over long distances, excluding difusion or contact of info stored in matter

Practical long distance communication, which does not rely on the movement of encoded configurations of matter, from source to destination(odor,books,DNA,floppy disk), always involves waves (EM, ...
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1answer
96 views

“Book domino” propagation speed?

I was watching this video on the Guardian website. As it can be seen, the "wavefront" of the fallen books travel with a fairly constant speed, which I guess depends on the mass of the book $m$, on its ...
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1answer
81 views

Is information propagated across a medium in any other way than waves?

Is information propagated in any other way than waves? Please distinguish "propagation across a medium" from information "storage within stable states of matter", which might difuse or interact ...
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2answers
48 views

Problem in progresive wave

In this progressive wave we need to find out the phase difference. If we define it by $\phi$ in the x distance, we get . $$\phi = \frac{2 \pi}{\lambda}x$$ But when we write the prograsive wave ...
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1answer
50 views

Plane wave reflection

Using the plane wave reflection equation... $$1-R=T \space ?$$ I cannot find the symbol of reflection constant so i will call it as "L" 1+L = T What ...
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1answer
60 views

What if a probably non wave equation, satisfies the wave equation? [closed]

What does it mean for a function to satisfy the wave equation? Does it necessarily mean that it is a wave equation? Take for instance the function $f(t,z)=(at+b z)^2$. This function satisfies the ...
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1answer
63 views

Fourier Transform of E-Field with Decay Constant

Given an atomic transition with associated E-field $E(t) = E_{0}\cos(\omega_{0}t)e^{-t/\tau}$ where $\omega_{0}$ is the natural line frequency and $\tau$ is the decay constant of the simple harmonic ...
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0answers
64 views

What could be the distribution of an explosion energy of a mining-grade and seismic exploration explosives?

Seismic exploration involves the excitation of seismic waves using the industrially made explosive charges. What could be the distribution of explosion energy of such a charges? My guess is that it ...
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2answers
275 views

Doppler effect problem with moving mirror

This was the given question: A light beam of intensity $I$ and frequency $f$, directed along the positive $z$-axis, is reflected perpendicularly from a perfect mirror which itself is moving ...
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2answers
181 views

Does our existence cost us energy?

Anything when it needs to inform its presense such as electromagnetic presense of charged particles and gravitational presense of particles due to their mass does so by sending information of its ...
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1answer
355 views

Definition of the complex wavenumber

My syllabus of electromagnetism defines the complex wavenumber as: $$k = \omega\sqrt{\epsilon\mu}$$ with $\epsilon$ the complex permittivity and $\mu$ the complex permeability. Thus $\epsilon$ and ...
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1answer
212 views

Are matter waves transverse and can they be polarized?

Are matter waves transverse and can they be polarized? What I know:I'm aware of the de Broglie matter waves hypothesis and de Broglie wavelength relation(at a very basic level as part of high school ...
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1answer
124 views

The Mysterious Reverb in a Jar of Hair Gel

I have a small jar filled with hair styling gel (or, as it calls itself: Ultra Gel-Wax). The jar is cylindrical(with the height being less than the width), has an unscreweable lid and is made of ...
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2answers
174 views

Do water movement in the seashore represent waves? [closed]

I have seen water moving front and going back in the seashore.Do they represent waves?Explain.
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0answers
40 views

What is the physical meaning of group velocity for elastic waves through crystals?

In a chapter about phonons they define group speeds for elastic waves in crystals as the derivative of the dispersion relation: $$v_g = \frac{d{\omega}}{d{k}} $$ I wonder though how they come to ...
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2answers
169 views

A foundational question about harmonic motion : 2 pipes with different length and frequencies [closed]

How to solve the following question? A pipe open only at one end has a fundamental frequency of 256Hz. A second pipe, initially identical to the first pipe, is shortened by cutting off a portion ...
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1answer
84 views

Polarization of light

So for my experimental optics class, I had to create a device that would emit horizontally polarized light such that its intensity is independent of an incoming linearly polarized beam of arbitrary ...
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1answer
508 views

Harmonics in an open organ pipe

How to solve the following question? An open organ pipe has two adjacent natural frequencies of 500 and 600 Hz. Assume the speed of sound in the air 340m/s. The length of the organ pipe is? What ...
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2answers
87 views

Mode of vibration comparing Classical and Quantum waves

I'm now studying Quantum Mechanics, and I took a course on Vibration and Waves last year. I have been trying to make an analogy between classical and the quantum waves. Is it true that both the modes ...
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1answer
123 views

Amplitude and phase in vector wave field

Is it possible to make some separation of amplitudes and phase for a general vector-wave field? For example, like a paraxial approximation of a complex scalar field of the form $$\Phi(x,y,z) = ...
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3answers
204 views

How do EM waves propogate?

I have read about this and what i seem to know is that when charged particles such as electron accelerate they produce time-varying electric fields. These E-fields produce H-fields and the process ...
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1answer
60 views

What are natural sources of longwave radiation

I am studying now the Earth radiation balance and I came across the question regarding the sources of the long-wave radiation on earth surface. The only source of theses wavelengths indicated in the ...
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0answers
60 views

Boundary conditions for 2D helical waveguide

I'm interested in looking at standing wave solutions for the wave equation on a 2D annulus, with the twist that the annulus is "streched" in to a helix in 3D, but so that the rings themselves are ...
3
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2answers
998 views

Why do longitudinal waves travel faster than transverse waves?

I have learned that if a medium can transmit longitudinal waves and transverse waves, then the longitudinal wave will travel faster. Why is this the case?
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1answer
106 views

Is information about the speed of light hidden in its spectrum?

Can the speed of light in the vacuum (c) be inferred from the spectrum of light? If that is not the case is it possible to tell from lights spectrum that it has entered a different medium, e.g. can ...
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2answers
466 views

Difference between propagating and evanescent waves

Currently I am reading about super lens and came across these two waves, propagating and evanescent. If a negative index material is used as a lens then both propagating and evanescent can be passed ...
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0answers
54 views

Periodicity of interference pattern from two light sources?

If I have two sources incident on a surface at two different angles, how can I determine the periodicity of the interference pattern? I have a spherical source impacting a mirror and a photosensitive ...
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0answers
31 views

Light Apparent Brightness

Let's say I have a triangular light source. From that light source I want to calculate a pyramidal frustum (tetrahedron with no apex). How would I calculate the maximum bottom area where light would ...
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4answers
775 views

Why is distance between two successive nodes equal to $\frac{1}{2} \lambda$ in standing wave

I'm reading my textbook and it says the distance between two successive nodes is equal to $\frac{1}{2} \lambda$ in standing wave. If $\lambda$ here means the wavelength of the standing wave ...
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2answers
55 views

Vibrating system at angular frequency in a vibrating system

Can anyone clarify what does mean the angular frequency of a system in case of the vibrating membrane. Angular frequency is measured in radians per second, what does this have with the vertical ...
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0answers
168 views

Simulating the Interference Pattern of Fraunhofer Diffraction by a Single Slit

I'm attempting to simulate the Fraunhofer diffraction pattern due to a single slit. We know that the intensity at an angle θ is $I(\theta)=I_0Sinc^2(\beta)$ where $\beta=kb{Sin(\theta)\over 2}$ ...
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1answer
161 views

How to determine the positions of two points in a radial line by an intensity level dB?

The following is the question from my school. A source emits sound uniformly in all directions. A radial line is drawn from this source. On this line, determine the positions of two points, 1.00m ...
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1answer
237 views

Deriving the group velocity of a wave produced by some basic cosine waves with unequal amplitudes

Consider some basic cosine waves of the form ${E_i} = {E_0}\cos ({\omega _i}t - {k_i}z)$ with different amplitudes, frequencies and phases. We know a combination of such waves could result in a wave ...
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0answers
25 views

Question regarding waves squeezed

in one MOOC I am taking, the professor had a slide stating "when squeezed into a narrow space wave is amplified". I am not sure I understand what he meant by that, and I am trying to think into terms ...
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1answer
99 views

Plane Wave expansion method

I really don't know if this is the right forum to ask the question...but please help me if you can!! I was going through the Plane Wave Expansion Method Derivation...But to be honest I could not find ...
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1answer
176 views

Work Done by Vibrating String - Without Small-Amplitude Assumption

I'm trying to derive the equation for work done by a vibrating string, but I'm running into problems. The easiest way - the method used by the other question by this name - makes the approximation ...
2
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2answers
131 views

How do waves meet at a single point?

In principle two objects can never meet,because of electromagnetic repulsions for example if I touch something, I am not actually touching it considering the fact that there is a small region left due ...
3
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2answers
340 views

Do Electromagnetic Waves really propagate through continuous Induction?

I've often seen it said that in an Electromagnetic Wave the changing Electric Field component creates the Magnetic Field Component and the changing Magnetic Field Component in turn creates an Electric ...
2
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0answers
252 views

Chladni Plate Mathematics

I am a high school student doing an IB Extended Essay investigation concerning the resonant frequencies of Chladni plates of differing materials and sizes. Would someone please explain the definition ...
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41 views

Why is a $\pi$ phase added on reflection and why do things change with absorption? [duplicate]

Mathematically, how does a $\pi$ phase shift appear upon reflection of light off a optically denser medium? Why is it always $\pi$? If the medium is absorptive it is no longer $\pi$?