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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9
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2answers
134 views

Momentum of transverse waves on a string

In general, if a wave carries energy density $u$ with velocity $v$, it also carries momentum density $u/v$. I've seen this explicitly shown for electromagnetic waves and (longitudinal) sound waves. ...
13
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2answers
169 views

Rope waves with a twist

In the picture you see a person walking a slackline. A slackline is a tensioned flatband of polyester. Typical tensions are between 1 kN to 15 kN depending on the length of the line. The lines are ...
7
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2answers
81 views
+50

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? ...
4
votes
2answers
240 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 ...
-3
votes
1answer
27 views

light and sound speed [on hold]

why is the speed of light faster in water than it is in air? And why is the speed of sound slower in liquid than it is in air? Is its difference is related to wave's appearance? like transverse wave ...
1
vote
0answers
29 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 ...
1
vote
1answer
35 views

Calculating wavelengths from angles in a diffraction grating? [on hold]

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 ...
-1
votes
0answers
12 views

How much heat can ULF RF waves can generate? [on hold]

How much heat can ULF RF waves can generate? Can the heat generated from RF waves burn of insects wings which are in flying state?
0
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1answer
212 views

Why does amplitude of a mechanical wave increase and then decrease with increasing driving frequency?

I was doing an experiment where I explore how the frequency of the oscillation of a vibrating water hose (the end of the water hose), affects the amplitude created by the water path (a wave-like ...
2
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1answer
41 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?
0
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0answers
9 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?
0
votes
2answers
29 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, ...
-2
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0answers
27 views
4
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2answers
42 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 ...
6
votes
0answers
30 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 ...
6
votes
2answers
388 views

Wave packet in curved spacetime

It is known that the classical equation of motion for a scalar field wave packet on a curved spacetime background gives the geodesic trajectory (the e.o.m. is $(\nabla_\mu \nabla^\mu + m^2) \Phi=0$). ...
9
votes
2answers
87 views
+50

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 ...
-1
votes
1answer
63 views

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

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) ...
1
vote
1answer
34 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 ...
4
votes
1answer
59 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 ...
0
votes
0answers
41 views

Why does light propagate rectilinearly? [on hold]

I found a question: Light propagates rectilinearly because of its: a. Frequency b. Velocity c. Wavelength d. Wave nature. Now the answer given in the reference is wave ...
4
votes
2answers
181 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 $\xi_2(x,t)$. ...
0
votes
2answers
110 views

What is the least count of the timer clocks used in RADAR?

I was checking out some videos in YouTube regarding the working principle of RADAR. To quote some HOW IT WORKS: World War II Radar (720p), part 1, How does RADAR work? | James May Q&A | Head ...
0
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0answers
16 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 ...
0
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0answers
34 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 ...
3
votes
0answers
51 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 ...
0
votes
1answer
36 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 ...
0
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2answers
40 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 ...
7
votes
4answers
3k views

Is speed of sound really constant?

Does not speed of sound actually depend on the frequency and/or amplitude of the waves? If so, why it is constant?
2
votes
1answer
52 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
votes
1answer
24 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 ...
1
vote
3answers
25 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 ...
0
votes
4answers
10k views

Does increasing the tension on a string also increase the density?

Consider a string under tension, for example, a string on a guitar. When a guitar string is plucked, it vibrates at a certain frequency. When the tension on the string is increased by twisting the ...
1
vote
2answers
41 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 ...
3
votes
1answer
26 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: $\Omega = (0, 0, \Omega)$ ...
4
votes
1answer
77 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 ...
0
votes
2answers
32 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 ...
4
votes
2answers
48 views

Do longitudinal waves travel more quickly in denser gases?

I understand that sound waves are longitudinal, and they travel faster in water than in air. However, would this imply that longitudinal waves travel more quickly in denser gases?
0
votes
2answers
37 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 ...
0
votes
0answers
17 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 ...
1
vote
1answer
27 views

Conservation of energy in a sound wave

I have two ultrasonic transducers, an emitter and a receiver, and I'd like to know how the energy of the spherical wave is conserved. I guess the energy is proportional to its amplitude and it ...
3
votes
2answers
207 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 ...
2
votes
1answer
75 views

how can interference occur within diffraction?

My book says : The number of interference fringes occuring in the broad diffraction peak depends on the ratio d/a that is the ratio of the distance between the two slits to the width of a slit. In ...
3
votes
2answers
270 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.
-1
votes
3answers
70 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, ...
1
vote
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?
1
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1answer
58 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 ...
2
votes
0answers
21 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 ...
0
votes
0answers
19 views

Lattice light wave [closed]

It is desired to produce a lattice that provides five light maxium exposed to light with light of wavelength 540 nm, but which provides only three light maximum exposed to light with light of ...