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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The shape of speaker cones

This is related to another question I just asked, but they are different enough I thought it deserved its own spot. Speaker elements seem to always be shaped like a cone with a portion of a sphere at ...
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3answers
276 views

The physics of sound boards

As a kid I was bemused at why soundboards worked. A small sound could be demonstrably amplified simply by attaching the source to a surface that is rigid and not too thick. How could the volume ...
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5k views

The relationship between the energy and amplitude of a wave? Derivation?

From multiple online sources I read that $$E \propto A^2$$ but when I mentioned this in class, my teacher told me I was wrong and that it was directly proportional to amplitude instead. As far as I ...
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113 views

Can a wave exist on the “face” of a wave?

It would seem that this would be possible with waves in water. What about other waves Clarification: Given a wave starting from a point of impact, in water, at: Time 0:00 and xyz 0,0,0 and the ...
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1answer
280 views

Index of Refraction in Metal: Approximating Complex Perturbation

If you consider waves in a metal, you can write the index of refraction for the metal as, $$ n^2 = 1 - \frac{\omega_p^2}{\omega^2} $$ I am interested in what will happen if the index is perturbed by ...
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1answer
106 views

What does non magnetic and nonconducting mean in reflection and transmission of waves?

So, we were ask to consider the Fresnel Equations for parallel and perpendicular waves (with index of refractions). Then, we are ask to prove some equations in which "... for nonmagnetic ...
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34 views

How much can a thin layer of hi-speed material within a low-speed volume block a wave due to total internal reflection?

Consider a block of isotropic material with compression wave velocity associated with it, $v_1$. Consider a thin flat layer of high compression wave velocity $v_2, v_2>v_1$ that is buried within ...
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2answers
66 views

Other frequencies in a cavity

This is a fairly basic question but is something that I've never properly understood. If you have a cavity with perfectly reflecting walls, I understand that there are obviously frequencies which ...
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1answer
202 views

Principle of Superposition for driven oscillator

So I understand the the Superposition Principle states that all the forced oscillations, as determined by multiple external forces, are to be added up in order to get the entire solution. However, ...
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32 views

electron spin separation

I am having doubt whether the electron's up spin moment and down spin moment can be isolated from one another. If it got separated, will each moment acts as magnetic monopole (stable or unstable). ...
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4answers
658 views

Can frequency be equal to 0?

Is correct to speak about frequency equal to 0 ? $$f= \frac{1}{t} $$ If $t\rightarrow\infty$ can I consider that the frequency is equal to 0 ?
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3answers
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Speed of sound at temperatures below 0 °C

How can the speed of sound be calculated for temperatures below 0 °C (down to -40 °C)? Does the calculation $v=331\ \frac{m}{s} + 0.6 \frac{m}{s°C} \times T$ still hold (where T's unit is ...
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1answer
252 views

Can atmospheric pressure literally push electromagnetic waves?

I work for an IT company and some time ago we had an issue with our wireless internet. We are 5 miles away from the ISP's antenna. Our Sys Admin expressed the view that the electromagnetic waves are ...
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2answers
635 views

If electrons behave as standing waves when they are bound to an atom then how do they carry charge?

Today in my physics lesson we learnt that the best way of describing the behaviour of an electron that is bound to an atom is to treat it as a standing wave. I understand that this is the ...
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1answer
68 views

Convective derivative of oscillating fluid with bulk motion?

I have a fluid $u$, which comprises a zeroth order constant motion $u_0$ as well as a first order oscillatory motion $u_1$. The convective derivative is $$\frac{\partial u}{\partial t} ...
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3answers
210 views

Electromagnetic Waves

We all know that light is an electro magnetic wave. but is electricity a EM wave? If it is then why light does not requires a medium to travel and why on the other side electricity needs a conductor ( ...
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1answer
848 views

If the k of a wave is negative, is the wavelength negative too?

My friend went to an interview for a reputed scholarship program and was asked this question. A wave has an equation $a\sin(\omega t-kx)$. Sometimes k surely can become -ve. We know that ...
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0answers
109 views

Gerstner Wave Formula to Vertex information $(x,y,z)$

I have created a program, that draws a plane mesh, and allows to me edit or animate all the separate vertices along it. The idea behind it, is for me to be able to create a gridMesh based wave ...
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2answers
126 views

Beginner Physics - Explaining longitudinal waves

I am having difficulty grasping the concept of a longitudinal wave. My textbook definition "In longitudinal waves, the vibration is backwards and forwards in the direction of motion of the wavefront" ...
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2answers
65 views

Mechanical pulse reflection

When we have a rope with one fixed end and we send a pulse through it, the reflected pulse is inverted. My question is as follows - is it correct to say that near the end (when the pulse hits the ...
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0answers
25 views

Help with Hologram problem [duplicate]

Can someone help me out with a simple yet interesting 3D hologram related problem and solution, which can help me understand the subject and then teach the subject to a group of students.
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1answer
585 views

Simple Harmonic Motion Question - Block on Platform [closed]

A platform is executing SHM in a vertical direction with an amplitude of $5$ cm and a frequency of $\frac{10}{\pi}$ vibrations per second. A block is placed on the platform at the lowest point of its ...
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0answers
177 views

Inverse of the D’Alembert wave operator

Let $f(x)$ a solution of the wave equation $\square f(x) = 0$. I don't understand why the following operator $$ \mathcal{D} \equiv \frac{1}{2}(\nabla^2)^{-1} (x_0\partial_0 - C) $$ for arbitrary ...
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1answer
91 views

Wave equation in varying mediums

I recently stumbled upon the above image describing partial transmittance, and was wondering what sort of equation would model such a wave propagating through varying mediums. Is there also an ...
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1answer
4k views

Relationship between slit size and wavelength in diffraction

Almost in every book on physics we can find a statement like "diffraction gets stronger when the size of the slit is comparable to the wavelength". Let's say we have a wall in a bathtub with a slit in ...
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2answers
175 views

A theory about a travelling wave due to a vibrating rope seems to be contradictory, please spot what is wrong?

Consider a travelling wave produced by vibrating one end of a rope while the other end is made to freely move along a vertical line. Mathematically, the equation of the traveling wave that also ...
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3answers
654 views

Wave Function for a Sinusoidal Wave (Why minus sign?)

I was trying to understand how the wave function for a sinusoidal wave was derived, but did not understand one specific sign, the minus sign in the following formula: $$y(x,t) = A \sin(k x – \omega t ...
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187 views

How can one calculate the distance a particular sound will travel?

What do you need and how to calculate a distance traveled by sound? For example if you hit a bell with a specific amount of power how far will it travel?
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1answer
188 views

SIngle slit diffraction and location of dark spots

In single slit diffraction, why (according to the equation for $\theta$) do successive dark spots exist at whole number intervals ($n=1,2,3, \ldots$) and not half? The correct path difference for ...
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1answer
247 views

Electron and photon collision

So electron moving left ($v_{initial}=0.8c$) collides into photon going right. After the collision electron is moving to right ($v_{after}=0.6c$) and the photon is moving to left. What is the ...
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1answer
59 views

Can there exist a Wave which changes the quantum states of particles?

i'm a high school student and i was reading about electromagnetic waves and how they transport energy and that the electric and magnetic fields sustain each other. I have also read about longitudinal ...
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2answers
3k views

Why does noise affect FM radio less than AM?

Frequency modulated waves are less susceptible to noise compared to amplitude modulated signal. This is because the information in an FM signal is transmitted through varying the frequency, and not ...
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2answers
517 views

Why do waves diffract?

There have already been a lot of questions on this site on diffraction but I still believe this one might be slightly different. In electromagnetic waves, diffraction and any other phenomenon of wave ...
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2answers
995 views

Why are two independent sources incoherent?

Coherent sources are produced from a single parent source. But, why are two independent sources always incoherent? Two sources can produce light of the same frequency. Then, I guess the problem is ...
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1answer
99 views

What does (simple) $j/cm^2$ represent AND how does this result $6.959j/cm^2$? [closed]

According to the image shown below, this specific Laser Hair Treatment device claims that it has a concentration of $6.959 j/cm^2$. So far by research I have found that it needs around $6\mbox{ to }7 ...
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1answer
43 views

Diffraction from interatomic spacing

In diffraction from a single slit, we learn that the angular width of the central maxima, is given by $2\sin^{-1}\frac \lambda d$. For $d\approx \lambda$, the incoming wavefront should be spread to ...
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1answer
525 views

How far do air particles move when a sound wave passes through them?

How far do air particles move when a sound wave passes through them? I know that they don't actually travel, the question is how far do they oscillate or what is the physical amplitude of the ...
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4answers
2k views

Why do we calculate energy by integrate the Signal squared?

What's the interesting thing in the square of a signal? I know integrating gave us the sum of the differentiated energies, but why the Energy is the square of the signal?
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942 views

Do electromagnetic waves always move in straight lines?

When we send an electromagnetic short wave to the sky, it reflects due to the ionosphere effects. But if we send it horizontally, is it correct that it moves around the surface of the earth, and if it ...
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3answers
1k views

Could submarine SONAR kill a diver?

Could a diver swimming next to a submarine be killed or seriously injured by its SONAR? What physical aspect of SONAR affects the human body in a potential harmful way?
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1answer
217 views

Infinite potential square well solutions

My question is about understanding the different solutions of the potential square well. Imagine a square well defined this way: $$ V(x) = \begin{cases} ∞&\,{\rm if} x<0 \\ 0&\,{\rm ...
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132 views

Symmetry of wave pulse

How can one decide whether a wave pulse is symmetrical by looking at its equation? $$y(x,t)=\frac{0.8}{[4x+5t]^2} $$ represents a moving pulse will it be symmetric?
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3answers
324 views

How to calculate Standing Waves in Electrical Cables?

I have a 20 metre Coaxial Cable. I send digital signals down the cable ranging from 5 KHz to 50 KHz. I have noticed a pattern in the noise ratio, an oscillating wave. I predict this is to do with ...
2
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1answer
889 views

Can a macroscopic body have wavelength as that of electron? [duplicate]

Einstein has suggested that light can behave as a wave as well as like a particle i.e, it has dual character. In 1924, de-Broglie suggested that just as light exhibits wave and particle properties, ...
6
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2answers
204 views

Is it possible to estimate the speed of wind by the sound emitted by a cable of an overhead power line?

I was near ($\approx40m$) an overhead power line and I heard a sound coming from the cables of the power line; I think the sound was made by the vibrations of the power cables due to the wind but I am ...
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1answer
1k views

Can electron exist as a standing wave inspite of successive superposition?

With the development of quantum mechanics, it was found that the orbiting electrons around a nucleus could not be fully described as particles, but needed to be explained by the wave-particle duality. ...
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1answer
129 views

Diffraction of sound

The sound waves, by the virtue of it being a wave, shows diffraction and interference. But in diffraction, I learnt that if the wave is allowed to enter through a small aperture, there is a central ...
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3answers
425 views

Can we explain Huygen's principle taking into account Maxwell's predictions?

Descartes gave the corpuscular model (1637) of light. Corpuscular model was further developed by Issac Newton. Model predicted that if the ray light (on refraction) bends towards the normal then the ...
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3answers
201 views

Do electromagnetic waves have endpoints?

When learning about electromagnetic waves at school we never talked about any endpoints as we did with standing waves, so I assumed that light has an endless length, but that doesn't make sense. So my ...
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1answer
80 views

How does a transverse wave propogate in a medium?

I have been told that trasverse wave propogates by the oscillation of medium particles in direction perpendicular to propogation. Consider a wave on a taught string (x-y plane). What is the ...