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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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Theoretically, if I swish a laser back and forth fast enough/at the right frequency on a distant surface, will I get an interference pattern?

Just curious. I’m kinda stumped and am interested in how one would go about visualizing/calculating this.
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How to calculate the frequency of the waves [on hold]

Here a square wooden block is made to rotate 3000 times per minute. A springy metal strip presses against the block, as shown in figure below. A person nearby observes what is happening. Calculate ...
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Why are large speaker cones required to to produce loud low frequency sounds?

Is there any reason for why a small speaker cone cannot produce low end sound at a comparable volume to higher frequencies? I can understand how a larger speaker would be in contact with more air and ...
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What is the relationship between relativity and the Doppler effect?

My sister just watched this video about space contraction (Spanish), and asked me if this is related to doppler effect. In the clip they also introduce the idea that a bat would be affected by ...
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Why are displacements added algebraically during interference of waves , why not vectorially?

In the diagram (A) , the individual waves are crossing at an angle to each other , so the dispacemnt of the particle at their intersection must have an angle between them , and that must involve ...
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Stress and Strain in a standing wave

Where are stress and strain maximum in a Standing wave? what about a transverse wave? My book says "strain is maximum at the nodes in a standing wave". But since Antinodes are the position of maximum ...
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Division by 0 when calculating wave transmission and reflection coefficients

Perhaps more like a mathematical issue here... When we consider a wave propagating from medium 1 to a medium 2, boundary located at $x=0$, we have the following wave equations for the incident, ...
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Laser beam focus

Why isn't it possible to focus a laser beam to an infinitely small point in space? I am familiar with the shape of a gaussian beam, but why can't my $w_0$ be equal to zero?
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How do phase shifts affect standing waves?

So I understand that you get standing waves if there are waves of the same amplitude and wavelength traveling in opposite directions. But what happens if the wave traveling in an opposite direction ...
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Why must traveling waves have the same amplitude to form a standing wave?

I understand the reason for which the wavelengths of the incident and reflected waves must be equal: otherwise, the interference at any fixed position would be constructive at some instants and ...
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Issue showing that the phase of a harmonic wave is invariant under a Galilean transform

The phase $Φ$ of wave is defined as $kx-wt$. It should be the case that all observers moving relative to each other in the non relativistic case will agree on this. So given the transforms $x'=x-vt$ ...
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Amplitude of a wave, and boundary effects

I am curious as to what causes a discrepancy in the amplitude between the incident and the reflected/transmitted pulse. (* For instance, in the first image, the incident pulse seems to be of greater ...
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Why do we assume the reflected and transmitted waves are sinusoidal in the derivation of Fresnel's equations?

In the derivation of Fresnel equations, I often see the first step as writing down the equations of the incident, reflected and transmitted waves as sinusoidal. I understand why we do not lose ...
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Does superposition of all possible plane waves represent complete solution of Maxwell's equations in free space?

Consider the set of all possible superpositions of all possible "plane waves that satisfy Maxwell's equations in free space". Does this set represent all possible solutions of Maxwell's equations in ...
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Solution to Maxwell's equations in free space that are not plane waves [closed]

Are there solution to Maxwell's equations in free space that are not plane waves? I think there aren't. (Save trivial ones, i.e. E=const , B=const ) But i am not able to prove it. Please help. I would ...
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If sound is a longitudinal wave, why can we hear it if our ears aren't aligned with the propagation direction?

If a sound wave travels to the right, then the air molecules inside only vibrate left and right, because sound is a longitudinal wave. This is only a one-dimensional motion. If our ears are oriented ...
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Is there an equation to relate a glass's frequency to its mass when it's struck with a spoon?

The mass therefore would be changing because I am pouring in water and testing the frequency at different volumes. Obviously as the volume increases the mass increases and the frequency decreases. ...
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Total internal reflection of sound

Does sound experience the total internal reflection from a boundary of two materials, say, aluminum and copper? The Freshnel formulas for light depend on polarization. However, sound typically is not ...
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Are there different types of superposition?

In electrostatics or in gravitational, when we are talking about interaction between multiple charges or multiple masses, we say that the interaction between any two charge or mass is independent of ...
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Maxwell's equation in free space from wave equations of electric and magnetic field

How to go from the wave equations of electric and magnetic field and $$ \boldsymbol{\nabla}\cdot \mathbf E = 0 \quad \text{ and } \quad \ 0 = \boldsymbol{\nabla}\cdot\mathbf B, $$ to the remaining ...
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What are the Basic Properties of a Photon?

I want to grasp the idea of a photon. While researching, I have come upon many different ways of describing a photon, but have found "quantum of the electromagnetic field" to be most satisfying. ...
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Are wave equations equivalent to Maxwell's equations in free space?

In free space, do Maxwell's equations contain the same amount of information regarding electric and magnetic fields as is contained in the wave equations derived from them? If so, how?
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Calculating total number of fringes in Young's Double Slit Experiment

I know that the $n^{th}$ order maxima can be given by $\frac{n\lambda D}{d}$. But theoretically n can go up to infinity and the intensity will go down. However, is there any way to approximate the ...
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How do we get a expression for speed of light $\frac{1}{\sqrt{\mu\epsilon}}$ using Maxwell's equation? [duplicate]

I am a $12^{th}$ class student in India. I am quite new to these interesting concepts. And, I think I've learnt about electrostatics, magnetism, Maxwell's equations very thoroughly. But, my books ...
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Wave simulation without reflection on the boundaries [duplicate]

I would like to numerically simulate a wave (let's say in a string) with different boundary conditions: Fixed endpoints Periodic Boundless $\varphi(x, t)$ is the value of the wave (vertical ...
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Can a sound wave begin with rarefaction?

Some digital recording samples (audio files) of recorded acoustic sounds present sound waves which begin with rarefaction. Is this an actual phenomena that can occur or is it a result of sound ...
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Change in position of maximum with the angle of source light in YDSE

One of my friends named Karan, asked me the following question: This question puzzled me for an hour. (an hour is much when your Boards exams are the next day) I want to know how I can accurately ...
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How loud does a sound need to be to make pressure waves detectable by a camera?

I've seen Veritasium's video that describes how sound can be picked up by a camera by observing small movements of objects sensitive to pressure changes (bag of chips, aluminium foil, paper...). That ...
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If all harmonics are generated by plucking, how does a guitar string produce a pure frequency sound?

A guitar is a plucked instrument and it is played by plucking a string at an off-centre point fixed at two ends. In general, Fourier analysis tells that all harmonics (the resonant frequencies of the ...
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Total momentum of multiparticle eigenstates of discrete translation operator

I will try to frame my question using the transverse field Ising model in the low spin-coupling limit as motivation. I'll begin by discussing a case I believe I understand, that of eigenstates of ...
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Doubt in a figure which explains rainbow formation

This figure is given in wikipedia to explain rainbow formation, l know that if light travels from denser medium to rarer medium and if angle of incidence is greater than crictal angle light will ...
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1answer
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Deciding amplitude for Beats

I have two harmonic sound waves of nearly equal angular frequencies $\omega_1$ and $\omega_2$, and whose equations(which I have particularly modified for convenience), are $$s_1=a.\cos\omega_1 t$$ $$ ...
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Why wave graphs sometimes use space and sometimes time?

On some graphs representing waves, the horizontal axis is marked as space (x), on other graphs the horizontal axis is marked as time (...
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Questions on derivation of Rayleigh-Jeans equation

So it starts by assuming a cube cavity with length $L$ that acts approximately as a black body. [note: the cube length is $a$ but I'm using $L$ instead] Standing waves are formed inside the cavity, ...
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Single Slit Diffraction Experiment

How is possible for an interference pattern to be created from a single wave? Why is the central maximum twice as wide as the others?
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How wave propagation is explained?

Using phasors to represent [electromagnetic] waves allows to describe how some physical quantity changes with time in one specific point in space. I'm interested to know how can be represented ...
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Why does the frequency of a wave does not change on reflection and on transmission? [duplicate]

I wanted to know why the frequency of a wave does not change even on reflection or transmission and does it only depends on the source only.
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Dependence of electrostatic force on the surrounding medium

Two unlike point charges held at a fixed distance from each other. The force between them is measured. Then a brass rod is placed exactly in the midpoint of the line joining the 2 charges. Will the ...
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A bullet fired at a pendulum

I am taking a first year undergrad physics class (waves & modern physics), and the answer my book gives to the question bellow has left me a bit confused. Here is the question (excuse me if it’s ...
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Electric field and particle Vibration

Electromagnetic waves are produced when particles vibrates, then why the direction of electric field is considered normal to the direction of propogation of wave? When electric field vector always ...
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Magnetic field in double slit experiment using electron beams

Say I have an experimental setup like this for a double slit experiment using an electron beam instead of light. There is a magnetic field coming out from the plane of paper. So will we get an ...
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What's the difference between linearly polarised and plane-polarised waves?

To explain polarisation, my book gives an example of a transverse wave in a string, and explains as: Since each point on the string moves on a straight line, the wave is also referred to as a ...
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Why can all solutions to the simple harmonic motion equation be written in terms of sines and cosines?

The defining property of SHM (simple harmonic motion) is that the force experienced at any value of displacement from the mean position is directly proportional to it and is directed towards the mean ...
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How does Destructive Interference redistribute energy?

I have tried looking at the many other questions on a similar topic, however, they don't provide a definitive answer to my question. What I managed to gather so far, is that if a light wave is super ...
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Proof that light rays take the same time to reach the focal point of a lens

In a thin plano-convex lens, if the wave front is perpendicular to the lens axis, all of the rays are in phase and are focused at the focal point. Can we use the lens geometry to mathematically prove ...
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Light wave equation - normalized?

What is the logic between the first and second equations for the electric field? How did they do it and why do we need the x and y components to be 1 over root 2?
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To isolate a particular mode of vibration in a standing wave on a string

Suppose a string bound between two rigid end-points is vibrating and it is a combination of a number of normal modes of vibration, is it possible to isolate a particular mode of vibration in wave by a ...
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Why are there these other “harmonics” (violin-specific terminology) in violins?

I've often read explanations of how standing waves form on the string of a violin and their harmonics but there is another phenomenon I've never seen explained: When you play certain notes, musicians ...
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Is this derivation of the Doppler effect for sound waves valid?

I was recently considering how to justify the formula relating to the Doppler effect for sound waves to a group of eleventh grade students who are likely encountering it for the first time. The ...