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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Non-polarised light

We know the beam of light oscillates in electric field and magnetic field, both perpendicular to both the wave of propagation and each other. What does, however, a non-polarised beam of light look ...
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237 views

Can polarized light be unpolarized again?

I was just wondering if there could be a process that could unpolarize polarazied light. Is that possible?
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40 views

Does rain jam radio signal?

I have experienced several times that heavy rain seems to jam the signal a radio of a bus receives. The only explanation I have is that the rain drops also become weak emitters, if a radio wave hits ...
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32 views

Diffraction grating from first principles

I have realised that a lot of books and online resources fail to give a detailed treatment of the derivation of the diffraction grating interference pattern. Normally only the result is stated. I was ...
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2answers
36 views

Coupled oscillators and Normal Modes

Consider we have a system consisting of 2 arbitrary masses and 3 arbitrary springs connecting them horizontally and between fixed walls, and we want to obtain the motion of each mass after we input ...
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2answers
60 views

Superimposed state vs. zero amplitude state

Two equal amplitude wave pulses approaching each other through some medium such as a string may form a region of zero amplitude when they overlap completely. At this point, the location of overlap is ...
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32 views

Driven coupled oscillator [on hold]

Consider the following system consisting of 3 masses and 4 springs : Suppose i start to drive the system, for instance horizontally applying a sinusoidal force with frequency w to one of its ...
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1answer
151 views

Why doesn't amplitude affect the speed of sound?

I understand why amplitude doesn't affect the speed of the sound AFTER the 'leading compression'. The extra force provided on one stage of the cycle is countered on the other stage. But shouldn't the ...
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1answer
59 views

How does a non-diffracting beam form from a converging ring of illumination?

I am trying to intuitively understand the basics of the supplementary text of a recent publication from Eric Betzig's group on lattice light sheet microscopy (1). I am confused by the explanation of ...
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82 views

Waves and Newton's Third Law

I'm a really newbie in Physics trying to understand a bit about waves. Firstly, i'm using the Wikipedia's definition of wave , that is, as energy traveling through a medium/space without ...
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1answer
21 views

Intensity for Single-Slit Interference Pattern

In the derivation for the equation for the relative intensity of a single-slit interference pattern in my textbook, there is an assumption that I find a bit fishy. I know this equation works, so it ...
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44 views

Using physics in music?

If stereo speakers are connected to the amplifier "out of phase," one speaker is moving outwards when the other is moving inwards.This results in a weakness in bass notes, which can be corrected by ...
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106 views

How do we know that the Fourier transform of space is momentum?

How do we know that the Fourier transform of real space $x$ is the momentum $p$ space or for energy and time, receptively? What's the mathematical process and physical logic?
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434 views

Derivation of Green's Function for Wave Equation

In the textbook Modern Methods in Analytical Acoustics (Crighton-1992, Amazon link to 2013 edition) the following relates the 3D Green's function in the time-domain to the frequency domain $g(x-y)$: ...
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126 views

Questions related to resonance/standing-waves and sound

I understand resonance for a simple harmonic oscillator but not for more complex systems like standing waves. How can I be in resonance with the normal mode in an organ pipe? I understand that the ...
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54 views

Question on open organ pipe

Although open organ pipe is open on both ends, how standing waves are produced in a open organ pipe. Can someone explain with more clarity ?
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21 views

What affects the period and the frequency of a longitudinal vibration?

In a lab experiment, our objective is to observe the characteristics of longitudinal waves/vibrations. If we changed the mass and amplitude, I feel that they either affect the period and frequency of ...
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29 views

What specific type of light on the EM spectrum has the longest wavelength and has been defined? [closed]

I am aware that broadcast waves have the longest wavelengths, but is there a specific type of broadcast, or other, wave that we know has a longer wavelength than others? What is the wave with the ...
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2answers
35 views

What's the physical interpretation of an arbitrary normal mode for masses and springs?

Consider the following system consisting of 3 masses and 4 springs : I have learned that this system posseses three normal modes, corresponding to its three natural frequencies, say ...
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1answer
2k 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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3answers
67 views

Negative frequency contributions for very short pulses?

I am wondering if very short optical light pulses can have a Gaussian envelope? When I describe the pulse shape with a Gaussian than the frequency distribution has also a Gaussian shape. But if the ...
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Why do bass tones travel through walls?

I was in the shower while my roommate was listening to music and got to thinking about the fact that I could only hear the bass and lower drums through the walls. Why is this? The two possibilities I ...
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4answers
149 views

Why Light isn't like an Acoustic wave?

I just wanted to know why light isn't an Acoustic wave.Is it because light wave doesn't obey acoustic properties?
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1answer
17 views

Why doesn't linear wave theory produce phase velocities that agree with each other?

I'm not sure I understand the dispersion relationship for water waves. According to Wikipedia, the wavelength of ocean wave at arbitrary depth is given by: \begin{equation} ...
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1answer
57 views

Path Difference Due to Angled Incident Light

If light incident on a diffraction grating makes an angle $\alpha$ with respect to the normal to the grating, show how $$m \lambda = d\sin\theta$$ becomes $$m\lambda = d[\sin(\theta - \alpha) + ...
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40 views

Does there exist a hyperbolic relationship between frequency $\omega$ and wavenumber $k$?

As the title states, is it possible to derive a hyperbolic relationship in the form of $\frac{x^2}{a^2} - \frac{y^2}{b^2} = 1$ between frequency $\omega$ and wavenumber $k$ I have tried to start this ...
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4answers
105 views

Space orientation of light waves

Recently I've started to be really intrigued with the electromagnetic spectrum and bumped into this problem: According to the wave theory of light (or any electromagnetic wave, really), the magnetic ...
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Wave-Particle Duality in the Confinement of an Electron in a Box [closed]

According to the wave particle duality, one can say that an electron is both a wave and a particle. If we confine it in a box, it can only form standing waves at particular wavelengths, which leads ...
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What is meant by the “intensity” of light? [closed]

7.(A) For a rectangular metal surface with dimensions 5 cm by 3 cm, the threshold wavelength for the photoelectric emission of electrons is 246.0 nm. (a) Calculate the work function of the metal ...
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45 views

Radio wave propagation in ionosphere

Radio communication is based on the concept that a radio signal incident on the ionosphere is reflected if the frequency of the wave matches the plasma frequency. But what exactly happens? Is it ...
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13 views

Comparing the Intensity of a Point on the Screen to the Central Max (Double Slit Experiment)

For (b), I know that the following equation will give me the ratio of the intensities: $cos^2(\frac{dsin(\theta)\pi}{\lambda})$ I do understand the theoretical basis behind the formula. However, ...
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3answers
65 views

Doppler effect- will frequency continually decrease?

My problems: I know that when a person is moving away, the perceived frequency will be lower than the frequency of the source. However, in the question, if the person is moving away, the ...
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3answers
109 views

Would this Produce Thrust? (Photon Momentum, Speed of a Pressure Wave)

This thought occurred to me after I began reading about the EM drive, and I know there are a lot of theories out there on how that works/doesn't work, I'm wondering why this solution wouldn't make ...
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1answer
34 views

Speed of an electromagnetic soliton in free space

What is the speed of an electromagnetic soliton in free space? Is it equal to 'c' ? P.S. My understanding of the Fourier transform says it's not.
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468 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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127 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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Why do prisms work (why is refraction frequency dependent)?

It is well known that a prism can "split light" by separating different frequencies of light: Many sources state that the reason this happens is that the index of refraction is different for ...
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2answers
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How do we count beats?

Books say that one beat constitutes two successive maxima of sound intensity with a minima in between. This is confusing me as the definition of beat period says - it is the time interval between two ...
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1answer
52 views

How does Huygens Principle explain interference?

How exactly does Huygens theory about the propagation of wavefronts account for interference?
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137 views

Are solutions coordinate invariant?

In the case of electromagnetism, we can solve the sorceless wave equation in Cartesian coordinates ($x$,$y$,$z$) getting plane waves as solutions: $$ u(x) = A(x-ct) + B(y-ct) $$ and actually I am not ...
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64 views

Particle displacement at a rarefaction or compression

In a longitudinal wave, why is there zero particle displacement at a compression or rarefaction and maximum displacement at a point pi/2 from it? Shouldn't it be the other way round?
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46 views

Polarisation definition

What is more correct and what is the difference? Polarised waves are waves with vibrations in one direction perpendicular to energy propagation "vibrations in one plane" "vibrations in one direction ...
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1answer
62 views

Doppler effect and light

Approaching the speed of sound in an aircraft is relatively difficult, because the closer you get to Mach 1, the denser the pressure is around you (sound accumulates causing vibrations). Is there a ...
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1answer
2k views

Does the absence of a sound particle indicate that there are no photons?

Sound is usually referred to as just "sound waves" - we do not talk about a "sound particle" and only as a wave or "matter wave." Could something similar apply to light i.e. that there really is no ...
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Plane polarized light?

I have heard about plane polarized light: light wave which has vibration in one plane. My curiosity forces me to ask a doubt, is there any way to produce polarized light wave which has vibrations in ...
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1answer
35 views

How does an acoustic guitar amplify its sound?

An essential part of a guitar is its hollow body. Without it, the strings wouldn't be very loud; as far as I know, the purpose of the body is to set up some sort of resonance and make the sound ...
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1answer
37 views

Reflected waves and phase changes

If a wave passes from a lightweight string to a higher density string, we say that the reflected wave has a pi phase change. Can we say that it has minus pi phase change? If yes, why would that not ...
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Unusual waves and one of its parameter

I'm messing up with this java app on the web about waves on a string and i'm really curious about something. The java app is the following : ...
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1answer
79 views

Oscillation of air particles and speed of sound wave

A sound wave is essentially air particles oscillating parallel to the direction of travel of the wave. We learnt that $v = f\lambda$, where $v$ is the speed of the wave, $f$ is the frequency of the ...
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3answers
219 views

The ubiquitous Planewave Ansatz

In physics, the planewave ansatz (meaning: an educated solution guess) is very ubiquitously used, when solving differential equations, in different domains of physics. E.g. to solve the dispersion ...