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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265 views

Wave speed derivation for small amplitudes

The above is a derivation for the wave speed equation in my physics textbook. However, I've read online that this equation is only true for waves with small amplitudes. I do not see where this ...
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1answer
39 views

Calculating wavelengths from angles in a diffraction grating? [closed]

I am having some problems calculating wavelengths from some given information about a grating spectrum. A diffraction grating with a spacing of 3μm is used in a spectrometer to investigate the ...
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0answers
10 views

Is it possible for wifi range extenders to deteriorate the quality of the original signal?

I am aware that wifi range extenders work by receiving and then re-transmitting signals, but does this process 'steal' any of the signal that I would usually use?
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2answers
39 views

Why do standing waves only occur in some specific conditions?

In the string which has both end fixed then the end point have to be $n (\lambda/2)$ from the beginning point in order to have standing waves. I know it has to start with a node and end with a node, ...
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1answer
46 views

Does amplitude of electric field and magnetic field vary with distance in em waves?

Does the amplitude of electric field and magnetic field of an em wave vary with distance?
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1answer
41 views

Mathematical definition of wavefront in case of non harmonic waves

What is the general mathematical definition of wavefront? Wavefront is the surface where, at fixed time, the phase is constant But for non-harmonic waves we cannot talk about phase as the ...
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0answers
57 views

advantages/disadvantages of a cylindrical microwave oven cavity in comparison to a rectangular cavity

Why are rectangular cavities preferred for standard microwave ovens with a frequency of 2.45 Ghz? What is the reason that you can hardly find a circular cavity? What are the disadvantages of ...
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2answers
46 views

Are two waves coherent iff they have the same frequency?

The essential property that two waves must own in order to interfere with each other is to be coherent. Two waves are coherent if their phase difference $\phi_2-\phi_1$ does not change in time ...
4
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1answer
64 views

Effect of motion of medium on frequency

Will the frequency observed by a stationary observer will remain same if only the medium between the source and observer is moving?(ie. both source and observer are at rest and wind is blowing from ...
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0answers
37 views

Can I measure the mode shape frequency of a metal frame with a sound meter

If I 'ping' a metal frame it will resonate in many different mode shapes with different frequencies. I can see those shapes by doing a modal FEA analysis. When I use a sound meter to measure the ...
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0answers
19 views

How to convert from overtone to harmonics and vice versa?

I was given this question: If the pipe length in a tube is 1.9 m, at the air temperature inside the tube is 28 °C, determine the fundamental frequency of the note played, fourth harmonic and the ...
3
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0answers
64 views

How can I prove that antinodes are present at both open ends of organ pipe mathematically?

I know that for anti node to be formed the magnitude of displacement should be maximum at there. For standing waves in an organ pipe, the boundary conditions are such that anti nodes are formed at ...
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1answer
66 views

How I can prove refractive index in an environment is this? [closed]

in "Applied Quantum Mechanics" by A.F.J. Levi, is a problem that I couldn't solve it can any solve it: if electrical filed is: $$ \mathbf{E}\left(\mathbf{r}, \omega \right) =\mathbf{E}_{0}\left(\...
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1answer
35 views

Why are phase constants of incident, reflected and transmitted simple waves equal in absolute value?

I was reading Griffiths's book of electrodynamics and i got stuck on the ninth chapter, where he analyses the propagation of a simple wave - fixed form and constant velocity - using travelling pulses ...
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1answer
37 views

Subtracting Audio from a Song with Multiple Forms

This question may start oozing into the realm of copyright infringement, but let's discuss the theory first and foremost. I have a song with vocal and orchestral accompaniment from a well-known movie ...
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1answer
26 views

How does string tension influence the harmonic spectrum?

Hey there fellow physicists & musicians! I have a question both physics and music related. How does the string tension affect the sound spectrum? More precisely, how do the respective ...
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3answers
31 views

When two waves interfere, how to calculate the amplitude of the wave?

As the theory of superposition of waves express the amplitudes of the interfering waves do algebraically sum up. But when we sum up the the total energies of a particle doing a harmonic motion due to ...
3
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1answer
31 views

Inertial Waves - Why neglecting the advecting term?

I'm trying to derive the dispersion relation for Inertial waves. In Cartesian coordinates: Inviscid and incompressible fluid is rotating uniformly with Angular Velocity: $\Omega = (0, 0, \Omega)$ ...
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2answers
47 views

Explanation of ray caustics in E&M

My understanding (now) of a real caustic is that it is envelope of curves or ray-paths that arise due to reflection or refraction from the medium/manifold. My main question is, I am seeing the term "...
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2answers
35 views

Will these two coherent electromagnetic waves be in phase?

My question is how will I know if two coherent electromagnetic waves are in phase based on their phase difference. I just solved a problem which stated... Two coherent sources A & B send ...
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2answers
43 views

Why doesn't the group velocity of a plasma EM wave equal the phase velocity here?

For plasma EM waves we have the dispersion relation $$\omega^2=\omega_p^2+c^2k^2$$ where the plasma frequency $$\omega_p^2=\frac{n_e e^2}{\epsilon_0 m_e}$$ One can show that $v_p v_g=c^2$, i.e., the ...
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0answers
19 views

How to create planar acoustic waves?

The only way I can think of for creating planar acoustic waves is using a 2D phased array of transmitters, but even then the planar wave is not so planar (depends on the interference pattern, which ...
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2answers
42 views

Wave speed derivation

The wave speed derivation approximates the wave as a circle. It uses that to know that a=v^2/R. However, numerous functions can approximate the wave. A straight line, x^2, x^3, etc. If I used those I ...
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0answers
24 views

How does a linearly polarized spin 1/2 wave look like?

Spin 1 waves are easy to illustrate and a linearly polarized spin 2 wave looks like this, but what is the counterpart for a spin 1/2 wave?
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2answers
286 views

Why does the length of a wind instrument affect it's pitch?

I understand how length of a string on any string instrument affects it's pitch, but I don't understand how a short wind instrument produces a high pitch.
10
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1answer
139 views

why interference pattern changes with given relation when the source slit changes?

Why for interference condition to be seen the dependence relation should be like $${\frac{s}{S}}<{\frac{\lambda}{d}}$$.Where $s$ is width of source slit and $S$ is the distance between the source ...
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1answer
61 views

what do we mean by speed of light dependent on direction?

I have a statement in textbook saying "When the speed of light is independent of direction,the secondary waves are spherical". Can someone tell when it is dependent on direction and how the secondary ...
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3answers
74 views

why doesn't pitch or volume change the speed of sound? [closed]

If sound is a propagated by particles hitting each other in a tranverse wave, why doesn't pitch affect the speed of sound? Since frequency is the speed at which the particles hit in a period of time, ...
4
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1answer
87 views

Are all diffusion-like processes described as wave-like in relativity-compatible formulations?

Citing from Wikipedia's article on relativistic heat conduction: For most of the last century, it was recognized that Fourier equation (and its more general Fick's law of diffusion) is in ...
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2answers
131 views

Pressure standing wave nodes at the end of the open side of a tube

I do not understand why standing sound waves can be formed in a one-side or two-side open tube. Consider a one-side open tube. In particular how does the reflection of the wave at the open end occur? ...
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1answer
14 views

Conditions imposed in wave reflection and transmission in one dimension

In the study of trasmission and reflection of waves in one dimension I do not understand completely the meaning of the conditions imposed. Consider an impulse $\xi(x,t)$ moving on a rope linked with ...
10
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3answers
175 views

Are mechanical energy of an element of a rope and energy density constant in the case of mechanical waves?

I'm confused about energy driven by a wave. Consider a sinousoidal wave moving in a rope. In my view each element $dm$ of the rope follows a simple harmonic motion in time. That means that the ...
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1answer
20 views

How do you tell direction and what's positive or negative in wave functions?

$$y = 1.00 \sin(5x − 2t)$$ So if I'm given $y(x,t)$, it's pretty clear what the amplitude, angular frequency and $k$ value appear to be. However, when I'm doing homework problems, the angular ...
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2answers
194 views

Standing wave on a rope fixed at both sides: minus sign in the reflected wave

I'm studying stationary waves on a rope fixed at both sides. In some books I find that the wave function studied is the sum of incident wave $\xi_1(x,t)$ and of the reflected wave $\xi_2(x,t)$. $$\xi(...
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1answer
14 views

Trasversal wave on a rod velocity

What is the velocity of a trasversal wave on a metal rod? Does it depend on the shear modulus $G$ $$v_{t}=\sqrt{\frac{G}{\rho}}$$ Or on the tension $T$ of the rod? $$v_{t}=\sqrt{\frac{T}{\rho}}$...
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0answers
34 views

Is disturbance propagation velocity equal to wave velocity in a solid body?

How do the disturbance propagation velocity and wave propagation velocity relate to each other? To explain my question in details I will describe the following situation from the theory of acoustic ...
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0answers
14 views

Half-life time of audible acoustic waves under given circumstances - is this model valid?

I need to find the half-life time of acoustic waves, given the information, that they are audible as long as their intensity $I > 10^{-12} W/m^2$ and the maximal distance $x$, where they are still ...
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1answer
18 views

Intensity of the acoustic waves coming out of the speakers at the very beginnig of their “journey”

According to the formula, the intensity of acoustic waves at any given point is: $$I(R) = \frac{P}{4\pi(R)^2}$$ where P is the power of the source and R is the radius of the force (Assuming that the ...
3
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1answer
54 views

Energy in a sound wave possible error?

In a certain text discussing longitudinal waves it stated that for a sound wave, both the kinetic energy and potential energy are maximum at the same time. I always thought that the potential energy ...
0
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1answer
28 views

Relation between variation of tension and frequency of a standing wave

What is the relation between a variation of tension and the variation of frequency of standing wave in a rope? I get this expression differentiatin the relation between $f$ and $T$ $$f=\frac{1}{2L \...
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0answers
37 views

Photon transmission

I want to know exactly how light travels. Are each photon in a light beam traveling in a cosine function? I'm confused because only when it goes through polarization that it starts to show this type ...
0
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0answers
28 views

Gravitational waves' Amplitude

Gravitational waves are disturbances in gravitational field which in turn is the curvature of space-time. So my question is it possible to somehow measure the amplitude of a gravitational wave and if ...
3
votes
1answer
67 views

Wave speed of a hanging rope

Let us consider a homogeneous rope hanging from the ceiling. I will call the vertical direction $x$ and the horizontal displacement $y$. When we apply the second Newton's Law to a portion of mass $\...
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0answers
39 views

Mechanical energy in an harmonic wave and in normal modes

I think I miss something about energy of a mechanical wave. In absence of dissipation the mechanical energy transported by an harmonic wave is constant. $$E=\frac{1}{2} A^2 \omega^2 m$$ But, while ...
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1answer
29 views

Measured organ pipe eigenfrequency does not match the theory

There are many well-known homework assignments to find eigenfrequencies of an open organ pipe leading to the solution for the fundamental frequency of such a pipe: $$f_0 = \frac{c_0}{\lambda_0} = \...
0
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1answer
30 views

Problem with linear mass density of which varies according to the law $μ = kx + a$

I have some problem solving this exercise: A wire of length $L = 10$ m has a linear mass density of which varies according to the law $$μ = kx + a$$ with $k = 1.8$ g m-2, $a = 0.5$ g m-1. The wire is ...
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2answers
26 views

Finding Amplitudes of Resultant Mechanical Waves

Let's say I have two arbitrary mechanical waves $y_1$ and $y_2$ propagating on a string in the same direction. The waves $y_1$ and $y_2$ differ in phase by an arbitrary angle $\phi$ and the ...
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3answers
33 views

Explanation as to why the sum of two sinusoidal waves, differing by only phase, can be represented by $2y_{m}\cos(\frac{1}{2} \Phi)$

How does the addition of two waves, differing only by phase, collapse to $2y_{m}\cos(\frac{1}{2} \Phi)$? Wouldn't the $\omega$ component of the wave still come into play given that it determines the ...
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0answers
10 views

Acoustic energy

Let's Assume that I'm sitting in a hypothetical container(room) whose 6 walls are PERFECTLY AND IDEALLY rigid and also are PERFECTLY reflective. Now if I start speaking anything in this room and so ...