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Questions tagged [waves]

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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How is the envelope of a wave derived from the wave equation?

I'm reading this book about electrical properties of materials where the electron is introduced as a wave. Using the equation of a wave, they bring about the "envelope" of a wave. So here is how the ...
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Chladni Patterns (Length Factor)

I've recently been conducting experiments on the Chladni Plates, testing out how the length of a square Chladni plate (and consequently its area) affects the frequency at which each respective chladni ...
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Speed of a transverse wave in a solid medium

Based on the analogy with sound waves, can we say that the speed of a transverse wave in a solid medium is, $$v = \sqrt {\frac {G}{\rho}}$$ Where, $G$ is the shear modulus of elasticity of the medium ...
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Transverse modes in optical resonators

Im struggling with understanding transverse modes in an optical resonator or laser. Hopefully you can solve this mystery for me. Thank you very much! As far as I know, there are two types of modes: (...
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Is this true about waves?

Once in a discussion with my teacher about mechanical waves he told that in a system containing a wave generator and reflector, the node number $n$ between these two things will be always integer. ...
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Mathematical expression of stationary wave [on hold]

Help me understand the equation of stationary wave. How it works?
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Plasma Waves at Different Frequencies

I am trying to determine what plasma waves appear at what frequency ranges. Particularly, I am interested in exploring plasma waves occurring between 100kHz to 1MHz. Is this a bad frequency range to ...
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How does a sound box amplifier work?

I read in a few places that in a guitar for example, the vibrations are passed through the connectors to the wood and the wood with its bigger surface is more efficient as a coupler to the air, ...
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Relation between amplitude of a wire and resonance [on hold]

The amplitude of a wire is $A = c/(a+b-c)$, under what condition resonance will occur? In my physics book I cannot locate a relation between amplitude and resonance frequency. I know amplitude becomes ...
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Phase difference equation doubt

I can't understand the explanation given by the book for the negative sign. Can you please explain? Thanks in advance. From the e-book: Phase difference between two points on a wave Let us ...
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Are Wavelets Just a geometric method for understanding how a wave moves forward or are they an actual thing?

Wavelets are emitted from every point on a wave towards all directions is what I read on a book but on another book I read Wavelets are emitted towards the same direction of the wave. And They create ...
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Problem in finding the velocity of a wave

In my textbook, the equation for a wave is described as : $y = A \sin{\frac{2\pi}{\lambda}(vt-x)}$ Now in this equation $x$ is variable as well as $y$. So when we will differentiate the equation by ...
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No standing wave at high tension [closed]

Why transverse standing wave in a string is finished when there is a very high tension in string .......I don't know the reason if tension increases speed then why there is no wave
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Water Hammer - Max Pressure Position

When using the Joukowsky equation: P=cpu To find a pressure rise in a pipe due to water hammer. How can I find the position along the pipe from the valve closure where the pressure rise is the ...
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How do we hear harmonics and how does it affect audio fidelity?

First and foremost, do we hear a sound wave as a sum of all the individual harmonics, at the fundamental frequency, or do we hear all the associated harmonics above the fundamental frequency and ...
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Elementary derivation for the minima of the interference pattern in the case of a thin wire without referring to the Babinet principle

For the single slit there is a well known elementary derivation along the following line: If the path difference $\delta$ between the elementary waves coming from the borders of the slit is one wave ...
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If strings are solid, why don't they have longitudinal waves? [closed]

A string is a solid but it does not show longitudinal waves. Well it is known that a string cannot be compressed but only be given tension but a answer with a sound scientific reasoning will be ...
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Mathematical equation for oscillating Wave produced in elastic surface membrane? [closed]

The equation will have following consumption: The elastic membrane is hit by a solid object to create of waves. Since the membrane is elastic it will oscillate back and forth and lose its energy. The ...
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Interference of two wave

We can produce a standing wave by superposition of two waves:one incident $y_1=A \sin{(kx-wt)}$and the other one is reflected $y_2=A \sin{(kx+wt)}$ ; (1)According to my teacher, if the two waves has ...
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why doesn't EM waves get weaker as we travel further away from the source [duplicate]

I know that as we get further away from the charge or from the magnetic field source both magnetic field and electric field decreases ,so why don't electromagnetic waves get weaker as the travel ...
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Feynman’s Treatment of an Opaque Wall

First time poster. I’ve been reading Feynman’s Lectures on Physics, and I’ve just finished reading his treatment on diffraction. Feynman described a method of thinking about an opaque wall that was ...
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Amplitude and Wave Speed

On this wave animation website, I noticed that on the section titled "From high to low speed (low density to high density)", there's an animation of a wave losing amplitude as it goes from a low ...
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How to find equation of simple harmonic motion from positional information at 3 different times?

Given a particle at three distinct position $x_1, x_2 \ and \ x_3 $from equilibrium position at different times $ t_1, t_2 \ and \ t_3 $ how can we find the amplitude, frequency and initial phase? It ...
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Transfer of momentum from a wave to it’s waveguide based on theta and the inertia of the wave?

Bit of a complicated one - I've been trying to understand how the energy in a wave dissipates or transfers it's energy to the walls of a wave guide as the angle of the wave guide changes. As the ...
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What happens to energy when waves cancel out? [duplicate]

So this is basically What happens to the energy when waves perfectly cancel each other? again, but I'm not understanding the answers given (or they don't address what I am confused about) Basically ...
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Is the direction of the electric field relative to the magnetic field in an electromagnetic wave a convention?

In an electromagnetic wave. Could the magnetic field be mirrored around the xy-plane? Is there a specific reason that the 2 fields are oriented this way? Is it just a convention?
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How to find the length of a copper pipe, open on both ends, to produce a certain frequency? [duplicate]

For example, to find the length of copper pipe needed to produce a freq. of 1046.5Hz, using the Length-Wavelength relationship of Wavelength = (2/n)*L, I rearranged it to L= λn/2. Problem is, to ...
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How to find length of copper pipe needed to produce certain frequency?

I have the basic $f=\frac{v}{\lambda}$. For example: C6 has a frequency around 1046.5 Hz. How do I find the length from this formula?
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What type of interference would occur between two frequencies that share the ratio 2:1?

Let's say I have two sine wave oscillations of 200Hz and 100Hz playing at the same time - what type of interference will I observe and why?
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What is the basic difference between beats and stationary (standing) waves?

As far as I know both are formed from interference of 2 waves. And why don't the stationary waves undergo destructive interference? It's a bit confusing.
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How to decide equation of a wave? [duplicate]

I was a bit confused about equation of waves. I encountered 2 wave equations: $$y(x,t)=a\sin(\omega t-kx)$$$$y(x,t)=a\sin(kx-\omega t) $$ What is the difference between them? Can anyone please ...
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Slowly-varying envelope approximation: what does it imply?

I understand that the slowly-varying envelope approximation means that we can write an electromagnetic wave as $$ E(x,t)=V(x,t)e^{i(k_0x-\omega_0 t)},$$ where $$ \left \vert \frac{dV}{dx} \right \...
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Sawtooth synthesis using random harmonic phase

I was experimenting with Octave and NumPy/SciPy by synthesizing (reverse) sawtooth waves and decided to find out what a sawtooth comprised of harmonics with arbitrary phases would sound like. Note ...
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Fourier transforming properties of a converging lens

Following Goodman's Introduction to fourier Optics argument I understand that a converging lens will introduce the following difference in optical path (see pag.158, 4th edition) $$r^2/2f$$ where $r$...
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What is meant by a longitudinal electromagnetic wave?

I reckon this is most likely a rather obtuse question, but I was wondering what would be meant by a longitudinal electromagnetic wave? Questions such as this one refer to there being 'no longitudinal ...
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Diffraction limit (Rayleigh criterion) and circular image on the screen

In the angular resolution, we explain the diffraction limit (Rayleigh criterion) by showing a circular image on screen. I wonder is there an inbuilt assumption that light source is a point source.? I ...
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Which has a higher a higher frequency - high velocity long wavelength or low velocity short wavelength

Since frequency is defined as the number of wavelengths passing through a point in a given time period, will a high velocity long wavelength wave have a higher frequency than a wave with a tenth of ...
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How is the behaviour of an atom particles as the atom approaches the speed of light? [duplicate]

There are many questions regarding what it means to accelerate the constituents of an atom towards to the speed of light, but I am not able to find any cogent article as to what the dynamics of the ...
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Propagating sound waves on a 3-D semi bounded domain

So in my course notes, we are investigating a sound wave that is propagating through a rigid cylinder with radius $R$. The wave equation is given in cylindrical coordinates as $\dfrac{\partial^2 \Phi}...
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Phase Velocity Derivation

I spend few hours trying to derive phase velocity of sinusoidal wave $$\cos(kx - \omega t).$$ I know that it must be equal to $\omega \over k$ but after banging my head for few hours and trying to ...
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Wave equation IVP on arbitrarily shaped 2D domain

I’m interested in simulating a wavetable of arbitrary shape. Formally, suppose $R ⊂ \mathbb{R}^2$ is a region whose boundary is a simple closed curve $γ$. Let $u = 0$ on $γ$, and let $u$ satisfy ...
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Average square Euler's formula for trigonometric identities

We know that the average value for a squared cossine on a full period is: $$\frac{1}{T}\int_0^T\cos^2(\omega t)dt=\frac{1}{2}$$ And the same value holds for a sine. But if we use Euler's formula, then:...
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Electromagnetic Waves - Amplitude

If light travels as a wave rather than a straight line there should be a width limit for it to travel and penetrate matter - like a hight limit for automobils in roads due to bridges - My question ...
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Sound Waves concept problem

I am a student . I am trying to understand sound waves. The book which I have got says: In these longitudinal waves there is a phase gap of π/2 between the displacement and pressure waves. If Y= A ...
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Why do musicians stretch the strings of their string instruments? [closed]

I came across this simple problem:´ A violin string has a density of $\rho=4.0\times 10^{-4}\space Kg\space m^{-1}$ and a length $L=0.33m$, and we want it to vibrate at a frequency $f=660Hz$, what ...
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Effects of oscillating objects on doppler shift on moving objects

For some reason I've been thinking about this for a couple of days: Say I have two aircraft almost identical in weight and shape. Although one of the aircraft has a propeller that can rotate at any ...
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Snapshot and history graph of wave

[] I don't understand why the wave is moving to the right, the x graph is showing downward movement and the right graph is showing upward with time. please explain better than the statement in the ...
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What causes the wave velocity of longitudinal waves in a spring to changes as its length changes?

This video shows the velocity of longitudinal waves changing in a slinky spring as its length changes: https://youtu.be/y7qS6SyyrFU?t=17 Something else responsible for the change in velocity ...
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How can we relate the wavelength of light to the length of a transmission line?

For the wavelength in free air we have $\lambda = \frac{c}{f}\, [\rm{m}]$, but how does it relate to the length of a transmission line? My question is because of the following example from this site: ...
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What happens to the pressure time graph when two musical instruments play at the same time?

I'm learning acoustics for the first time and I'm having trouble picturing what the pressure time graph would look like when two instruments play together. https://newt.phys.unsw.edu.au/music/flute/...