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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What is difference between the miltary radar in 1940's from commercial antenna that is for the use of TV

What is difference between the miltary radar in 1940's from commercial antenna that is for the use of TV? I have read article from some of the WW2 history website that call the German radar the ...
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4k views

Geometry of wireless signal strength

How does wireless signal strength correspond to distance? RSSI lies between -100 and 0 (at least, on my computer). Let's say I walk a distance x towards the router, and my RSSI goes from -60 to -50. ...
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26 views

Standing waves due to two counter-propagating travelling waves of different amplitude

Suppose I have two counter-propagating travelling waves of the same frequency but of different amplitude, like the transverse waves produced in a string by partial reflection off an endpoint. I read ...
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40 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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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 ...
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43 views

Why would a decreased length mean a higher frequency of sound?

This is in terms of the Water Bottle Lab: adding water (effectively decreasing length) to a bottle and finding its fundamental frequency at different lengths/amounts of water. I understand what ...
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44 views

Why can a wave only have a single frequency if it goes on to infinity?

I have read that the only way a wave can have a single frequency is when it goes on for all infinity. Could someone explain me in plain english the reason?
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64 views

Why Counter waves are being produced in water?

While studying water waves in a cuboidal tank, the following observation was made. A gentle tap on one side (A)of the tank, generated waves from that side towards the opposite (B). At the same instant,...
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93 views

Is double slit interference due to EM/de Broglie waves? And how does this relate to quantum mechanical waves?

I'm really confused about the fact that there seems to be two types of waves at play: the EM wave, which I understand to be an actual fluctuation of EM fields in space, and this other type of bulk "...
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57 views

Can every single sound ever made(from the beginning of time) be recreated again?

Sound is a wave and energy decreases as $1/r^2$ . The intensity of sound is proportional to $(amplitude)^2$ of the wave. So if we amplify the wave with some instrument then we can hear every single ...
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51 views

group velocity of acoustic waves

One can find the sound speed for the acoustic waves as follows: $\frac{\partial p}{\partial t} = -\nabla \cdot \rho \vec v$ (1) $\rho (\frac{\partial \vec v}{\partial t} + (v \cdot \nabla)\vec v)= -...
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35 views

Relation between the direction of propogation of sound and loudspeaker's diameter

Sound waves from a conical loudspeaker spread nearly uniformly in all directions if the wavelength of the sound is much larger than the diameter of the loudspeaker. Sound is essentially ...
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58 views

Moving an object in hand back and forth creates a gravitational wave?

Does moving an object in one's hand back and forth create a wave? It creates a changing gravitation field and that propagates as a wave, right? How does that differ from a "gravitational" wave that ...
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55 views

The image of a wall clock is to be obtained on the opposite wall 2m away by the means of a convex lens. What is the minimum focal length required? [closed]

I'm in 10th grade and this question came in my physics test. Nobody was able to answer this question correctly except my physics teacher who says that the answer is 2m. My answer is that there should ...
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1answer
120 views

How can a probability distribution have wavelength (de Broglie wavelength)?

The wave function described by Schrodinger's equation is interpreted as describing the probability of a particle in at any point in space, i.e. a probability distribution. Since this distribution ...
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89 views

Michelson Morley experiment - why is there an interference pattern in the first place?

In descriptions of the experiment, the two arms of the interferometer have the same length. There's an interference pattern which was expected to be shifted when the system was rotated 90 degrees. But ...
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71 views

Is this SISO (single input single output) or MIMO (multiple instead of single) system?

If I transform wave equation for vibrating string Mx′′+Cx′+Kx=b(t) in linear system using $x_1(t)=x(t)$ and $x_2(t)=x_1^{'}(t)$ vibrating string equation becomes $Md_tx_2(t)+Cx_2(t)+Kx_1(t)=b(t)$. ...
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104 views

Can sound reflect from itself?

If it is possible, what kind of conditions would be necessary? The case with electromagnetic waves could also be interesting, but I don't think that is possible.
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39 views

What is the distinction between a “ray” and a “wave” in optics?

What is the distinction between a ray and a wave in optics? From what I can gather, the only discernible difference is in nomenclature, where a ray simply refers to an EM wave with short wavelengths. ...
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28 views

Wave on a string to sound wave

If you have a string of 2m in length, and the wave speed on the string is 2m/s. and when then string vibrates at fundamental frequency the wavelength of the wave would then be 4m. However, the sound ...
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78 views

Question about the wave function of a travelling wave

I have a confusion about the wave function of a travelling wave. Suppose we have a wave function of a travelling wave travelling towards the positive direction of x axis $$ u(x,t)=A\cos\left(\omega(...
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1answer
49 views

The property of transparent lens [closed]

My question is this : what is the property of transparent material that is used for lens?. I think that it allows the light to pass through ( absorption property) and does not bend the light ( ...
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38 views

Why do higher frequency electromagnetic waves bounce of of smaller particles in the atmosphere but the lower ones dont?

I assume they have more energy but what is it more deeper and clearer than that that explains it?
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19 views

What parts of a string stretch most when a wave passes through it?

So there's a (transverse) traveling wave on an (ideal) string under tension. Why does the stretching occur around zero displacement? Why not at the crests?
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1answer
36 views

What are some of the empirical proofs of electromagnetic polarization? [closed]

I am aware of how polarization follows from Maxwell's equations, and how it is possible in transverse waves in general. I also know that Huygens, in his great Treatise on Light, first discovered and ...
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65 views

Books on waves with Fourier Transforms [duplicate]

There are many waves and oscillations books out there that also include Fourier analysis but very few give the subject a thorough treatment, they just pass it in a few pages. If anybody has any ...
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1answer
50 views

What justifies adding phasors' vertical components

I learned that, when superimposing two waves on top of each other to calculate the resulting wave's amplitude, it's helpful to use phasors. From what I gathered, phasors are vectors originating at the ...
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97 views

Physical meaning of wavelength of a EM Wave

The wavelength of a wave is defined as the spatial separation after which it repeats its shape. It is easy to visualize it for one dimension but if we consider a light wave/EM wave which is ...
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1answer
71 views

Molecular orbital theory

What I have learnt : When two waves overlap in phase, the resultant wave formed had a greater amplitude than that of the two interfering waves. When they overlap out of phase then the resultant ...
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1answer
122 views

What is slinky-approximation?

I was reading the derivation of wave-equation from Berkeley Physics - Waves by Frank S. Crawford Jr. Let $\Delta z$ be a small segment of a continuous string . At equilibrium, tension is $T_0$ at ...
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50 views

Zero stress boundary conditions for the acoustic wave function

When is it appropriate to use zero normal stress boundary conditions when solving the acoustic wave equation. That is when the pressure is equal to zero.
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68 views

Why use different arguments to plot a sine wave?

In my Electronics class was given some examples of sine wave graphs that represent voltage in respect to time, $v(t) = Asin(wt)$ and other graphs whose $x$ axis is $wt$ instead of $t$, like in the ...
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210 views

Wave equation - dissipation

The book states that the wave equation assumes no dispersion and no dissipation, with dissipation defined as a loss of energy and thus a diminution of amplitude. How can a spherical wave be described ...
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46 views

Is difference in wave number always small?

Over the last few days I have been looking at a derivation of group velocity. The derivation is the one shown in this question Deriving group velocity. I have seen this derivation in many places, and ...
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6k views

Why can't transverse waves travel through a liquid?

Can someone explain why a longitude wave can pass through the liquid, but a transverse wave can't. And can someone recommend some good animation of these processes.
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What is the wave propagated away from an impulsively excited spherical shell?

Consider a spherical shell of radius $R$ centered on the coordinate origin, and an impulsive excitation $\delta (t)$ distributed over its surface ('ie. a single layer'). Each point on the sphere’s ...
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84 views

The interference pattern of a wave along a line [closed]

Why the answer is B, but not C? Is it true that the pattern cannot go beyond $A_0$ and $-A_0$ at the same instant?
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1answer
157 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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532 views

Why are speakers louder in a corner?

You can test this very easily using an iPhone's speaker pointed towards a wall. When the speaker is more than an inch or two away, it is normal volume. However, when the speaker is nearly touching the ...
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90 views

Speakers and Changes in Temperature

Let's say that there is a speaker that oscillates the same way. Now, let's say there is a sudden drop in temperature. I know the speed of sound would drop. But, what will drop, the wavelength or the ...
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221 views

Doppler effect and acceleration's impact

Can anyone explain why they say Doppler effect does not depend on acceleration? Would having acceleration not affect the frequency? If the source emits the first circular wave, moving at 50 m/s ...
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amplification of magnetic field

can we by any means amplify magnetic signal as we can with electric signal. As both electric and magnetic field can be represented in the form of a wave the analogy seems to be natural. I want the ...
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50 views

Time dependency of the phase of a single photon

I am wondering if a wave packet of a single photon in the time domaine $$ \psi(t)=|\psi(t)|\; \text e^{\text i \varphi(t)} $$ can have a different $t$ dependence in phase than the simple phase $\...
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250 views

Wireless electricity through Wi-Fi power signal?

Could there be a method to obtain and send worldwide electricity through WiFi? I mean if we have internet everywhere and only need a WiFi device, can we apply the same to electricity technology? or ...
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227 views

Transmission of waves

How do you know if a wave will transmit when it hits a media boundary? Will a portion of the wave always be transmitted when a wave hits a media boundary? My textbook says part of the wave will be ...
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419 views

Intuitive explanation of the waves superposition

When the two waves collide, why do they pass right through each other? Mathematically it's due to the principle of superposition: the sum of the two solutions of a wave equation is also a solution. ...
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88 views

Does a light wave that has been cancelled by another light wave continue traveling forward?

I imagine that if a light wave is cancelled out by another light wave, it would still continue to exist as a photon that is traveling at the speed of light--only without a wavelength. Would it behave ...
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181 views

Ratio of energy of normal modes of string

Suppose there's a wave on a string represented by fourier series: $$y(x,t) = \sum_{n=0}^{\infty} (-1)^n \frac{1}{2n+1} \sin(nx)\cos(nct)$$ I know the energy is $\propto y^2 n^2$, where $y$ is the ...
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125 views

Is there just one fundamental frequency?

I read simple definitions of the terms frequency, and fundamental frequency, which defined them thus, Frequency: the number of occurrences of a periodic wave during a second Fundamental Frequency: ...
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How do the particles in a standing wave vibrate in phase within half a wavelength?

I would like to have a better understanding of phase difference when talking about stationary waves. How exactly are particles in phase within half a wavelength in a stationary wave?