Waves are disturbances that propagate through 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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Interpretation of Evanescent Elastic Waves for Material Damage

In elastodynamic theory, when the slowness vector is imaginary, the resulting elastic waves are called evanescent. I have read that this corresponds to exponential decay. I have also read that complex ...
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2answers
561 views

How does a vibraphone produce correct musical tunes?

As you might already know, frequency of musical notes is arranged in a such a way that if, for example, an A note has frequency of $x$, other A note which is placed one octave higher would produce ...
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3answers
78 views

Plane waves in special relativity

I don't understand how there can be plane waves that by definition are spread through all of space if nothing can travel faster than light. Wouldn't every wave have to spread over time with at most ...
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1answer
14 views

Sound source localization in cylinder

I am training an animal (let's assume it's a rat) to do sound-source localization in a cylindrical plexiglass chamber that is approximately 30 cm in diameter (see figure). That is, the animal must ...
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1answer
30 views

Wave nature of light [on hold]

I'm currently working on a project to demonstrate the wave nature of light. Now, my question in specific is: How could the phenomenon of interference be used to MATHEMATICALLY explain the wave nature ...
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1answer
27 views

Mathematical Relationship to find number of antinodes/nodes in a standing wave

So I have been learning about closed pipes (nodes at both ends), open pipes (antinodes at both ends) and open/closed pipes (node at one end and antinode on the other). I have also learnt that for a ...
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101 views

Can D'Alembert's Formula for the Wave Equation be used in Three Dimensions?

PART A) The 3D wave equation for spherically symmetric waves is $$\frac{\partial^2 u}{\partial t^2} = c^2 \left( \frac{\partial^2 u}{\partial r^2} + \frac{2}{r} \frac{\partial u}{\partial r} \...
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34 views

Why does the amplitude of the pulse never return to its original value when the number of waves used to construct it tends to infinity?

I was reading Constructing a pulse of Modulations, Pulses, and Wave Packets from Waves by Frank S. Crawford Jr. ; here, in the following concerned excerpt, the author is describing of constructing a ...
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4answers
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What is a standing wave?

I'm a highschool sophomore, bear this is mind when answering this question, in other words, the answer doesn't need to be in total layman terms, but it should be understandable by an applied ...
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2answers
47 views

Do radio waves from the Sun reach Earth?

Do radio waves from the Sun come into contact with Earth? If so, do they penetrate the atmosphere or are they reflected, absorbed, or scattered?
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1answer
41 views

What is the quantum (e.g. Photon) phenomena that represents the EM wave impedance?

The EM wave impedance of free space is said to be ~377 ohms and represents the ratio of Electric field strength (E) to magnetic field strength (H). So that: $$ \frac{E}{H} = ~377 \,\Omega $$ When ...
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6answers
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The speed of sound is a single value yet the speed of atoms is distributed over many values. Does the sound wave front smear out?

Sound waves travel with constant speed, but air molecules that transfer action move with different speeds than the ones described by Maxwell distribution. Why does the sound wave not smear out and ...
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1answer
135 views

Physical intuition on the integral contained in D'Alembert's Formula for the wave equation

If $\phi(t,x)$ is a solution to the one dimensional wave equation and if the initial conditions $\phi(0,x)$ and $\phi_t(0,x)$ are given, then D'Alembert's Formula gives $$\phi(t,x)= \frac 12[ \phi(...
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2answers
70 views

Properties of electromagnetic radiations with respect to wavelength [closed]

If two electromagnetic waves have same wavelength, does that implies both of them have same frequency and intensity?
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2answers
67 views

Does a wave have inertia?

In de Broglie hypothesis, particles have wave nature. The question is does this wave have inertia? If so is it represented in the corresponding wave equation?
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1answer
62 views

Which came first, the Crest or the Trough?

We were dealing with 'Interference of light' the other day in class, and our teacher mentioned the 'ripples in water' scenario......and well, that [and not interference in particular] became the bone ...
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2answers
47 views

Can sound waves be used as simple explanation of relativity effects in STR?

There are so many similarities (Doppler Effect, independence of wave velocity from source speed etc..). Try moving in your car with music and ask you friend outside record it while you moving towards ...
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1answer
14 views

Intensity of EMR and time dependence

I imagine an electromagnetic wave as the propagation of electric and magnetic fields. Consequently the amplitude of the field vectors are time-dependent. I also know that the intensity is ...
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3answers
1k views

Why is a wave pulse a superposition of sine waves?

I have learned that to construct a wave pulse, we need to superimpose multiple sine waves of different frequencies which all interfere to produce the pulse. What I don't understand is that a wave ...
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0answers
25 views

Why is the phase change of a reflected light ray one quarter wavelength?

Suppose a photon beam impinges on a half-silvered plate such that half of the photons are reflected and other half are transmitted. If $\lvert A\rangle$ is the state vector of the incident ray, and $\...
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3answers
86 views

What exactly is meant by the wavelength of a photon?

I've been thinking about this for quite some time, and from looking online I haven't found a satisfying answer. Lots of photons, such as visible-light photons have very small wavelength (which from ...
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1answer
24 views

Light scattering: Why is the natural frequency in air higher than the light frequencies?

In the Feynman Lectures on Physics Vol. I Ch. 32 (Radiation Damping. Light Scattering) it says: On the other hand, if we take the case of light in the air, we remember that for air the natural ...
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2answers
68 views

Why do smartphones need towers to send messages? [closed]

Why do smartphones need towers to send messages? Why can't they send messages directly to each other?
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1answer
69 views

In which-pattern does the individual-particles move in a longitudinal wave?

Transverse waves, such as upper-surface of pond-water, or in shaking-rope; the Transverse-Wave can be easily understood and drawn (for different times such as at t second, t + 0.25 second, t+0.5 ...
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1answer
26 views

Can the intensity of a sound wave in a minimum be greater than intensity in a maximum?

Suppose to have two speakers $A$ and $B$ one in front of the other, producing coherent sound waves with the same frequency $f$ and power $P$. In different positions on the line connecting the speakers ...
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2answers
96 views

Doppler shift and change in intensity of a sound wave

How are the intensity of a sound wave and the Doppler shift of frequency related togheter? That is, if the source or the observer are in relative motion, how does the intensity change? For a sound ...
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27 views

Nonlinear Saturated Schrodinger Equation in 1D- Physical Models

I'm studying the Nonlinear 1d Schrodinger equation $$i\psi _t + \psi '' + |\psi |^{2p} \psi - \epsilon |\psi | ^{2q} \psi = 0\, , \quad t>0, x\in \mathbb{R}\, q>p \, ,$$ and specifically, its ...
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1answer
21 views

Frequency shift in case of wind and no relative motion between observer and source

I've learned the following things about Doppler effect in the case of sound waves The Doppler effect formula is to be used in the air reference frame (where $v_{sound}=343 m/s$, at room temperature) ...
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28 views

Intensity of Radiation

In the textbook it says "the intensity of radiation at high frequencies (short wavelengths) is small." But I thought that high frequency= short wavelength= high energy= high intensity? What does the ...
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0answers
25 views

Standing waves on compound string

Please help with this question - No data is given as such. The 2 strings have different thickness. Initially, minimum frequency of the thick string is 120 Hz. Then if we push the cart such that only ...
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2answers
65 views

Trying to read phase shift constant from the graphs

I have an equation $y(x,y) = y_0 \sin (\omega t \pm kx \pm \phi)$ and there are two graphs. One is $y(x,t=0)$ in units $mm(mm)$ and the other is $y(t,x=0)$ in units $mm(s)$. Now I have to find all ...
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1answer
34 views

Group Velocity of guassian packet equals time derivative of mean position?

If I look at a gaussian wave package, and then interpret (in the usual Quantum-Mechanics Way) its square value as the propability density, then I can calculate a mean value for the position: $$ x_{...
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1answer
134 views

Is dispersion a property of medium or wave

I got a problem in learning Lewin's 'Vibration and Waves'. He first solve the eigenvalue of 5 beats connecting together and with fixed boundary condition. Then the velocity for different modes are ...
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37 views

Relative velocity between phase velocity wave and a group velocity wave

It is said that material particles have a dual nature. A particle is associated with a wave which travels with phase velocity and the particle travels with group velocity. These are related by $$v_\...
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1answer
29 views

Standing waves due to two counter-propagating travelling waves of different amplitude

Suppose I have two counter-propagating travelling waves of the same frequency but of different amplitude, like the transverse waves produced in a string by partial reflection off an endpoint. I read ...
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Beats: frequency of resulting wave vs. beat frequency

The beats frequency heard from the interference of two sound waves with frequencies $f_1$ and $f_2$ is $$\nu=|f_1-f_2|$$ Nevertheless the frequency of the resulting wave is not $\nu$ but the mean ...
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3answers
120 views

Significance of wave number?

Till now all I know about the wave number is its formula i.e. ${\frac{2\pi}{\lambda}}$. I always wanted to know what it really means. So can anyone please, explain me its physical significance?
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29 views

Conditions to find standing waves harmonics

I came up with a doubt on standing waves conditions. The type of question I find difficult to answer is of the following type. Consider a rope. I do not know if the rope is fixed at both end or at ...
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3answers
70 views

Can sound travel in the form of transverse waves?

We all know that sound is a longitudinal wave but in some books, I have found that sound travels in the form of both longitudinal and transverse waves while passing through rocks. Can anybody explain ...
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1answer
36 views

Situations in which there is path difference interference or formation of standing waves [closed]

I came up with a doubt about standing waves and path difference in general. Consider these two different cases as examples. If I have a rope fixed at one end and I make the free end oscillating, I ...
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3answers
531 views

Is there any effect on mechanical waves by electromagnetic waves (and vise versa)?

Do electromagnetic waves like light and gravitational waves (due to moon for instance) affect on mechanical waves like sound? Can sound change the path of light?
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Wave equation for odd spacetimes and source terms

It seems to be quite common practice, when solving the wave equation in spacetimes with odd topologies or horizons, to decompose the solution into a sum of the various origins (or destinations) of the ...
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1answer
40 views

Vibrations of a string [closed]

A string with length $L$ is stretched between two fixed points. The string can't vibrate with which wavelength? Four options are given, namely $L$, $L/2$ , $2L$ and $4L$. I know that the ...
4
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3answers
177 views

Why do we hear better during the night? [duplicate]

At night, we hear weak and far sounds approximately clear, while during the day we cannot. My high school physics teacher was saying that “this is because of interference of sound waves. During the ...
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2answers
2k views

Why do you only hear the bass when someone nearby is wearing earphones?

When someone nearby is listening to music through earphones or headphones, usually you can only hear the bass (unless it's really loud where you can hear the singer's voice and the other instruments ...
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1answer
60 views

Conservation of energy in interference of light

In interference of light, I know that energy is conserved globally but how the energy disappeared at minima appears at maxima? Is there any path by which energy flowed or is it just energy couldn't ...
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1answer
17 views

What happens when sound source is radiating through a hole in a cavity?

What happens to the external sound field , when loudspeaker attached to one wall is radiating inside a box and other wall has a aperture size of a diaphragm? Do we experience Helmholtz effect?
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3answers
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Water in glass tubes producing different pitches when tapped. Why exactly is this?

So I've been making a DIY instrument for my physics project at school. I decided to try this experiment where I put different volumes of water into a glass cup, and I tap it with a spoon to create ...
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2answers
52 views

What is the difference between real value and abs value? [closed]

I am confused here, though I have been reading about it for years. What is the difference between a real value and an absolute value? For example, when do we take the absolute value of pressure or the ...
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3answers
145 views

Minimum frequency of an electromagnetic wave

Is it possible to create an electromagnetic wave of near zero frequency? An electromagnetic wave carries energy. If we can make the frequency of an EM wave vanishingly small and make it practicality ...