# Tagged Questions

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 happens when sound source is radiating through a hole in a cavity?

What happens to the external sound field , when loudspeaker attached to one wall is radiating inside a box and other wall has a aperture size of a diaphragm? Do we experience Helmholtz effect?
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### Water in glass tubes producing different pitches when tapped. Why exactly is this?

So I've been making a DIY instrument for my physics project at school. I decided to try this experiment where I put different volumes of water into a glass cup, and I tap it with a spoon to create ...
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### What is the difference between real value and abs value? [closed]

I am confused here, though I have been reading about it for years. What is the difference between a real value and an absolute value? For example, when do we take the absolute value of pressure or the ...
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### Minimum frequency of an electromagnetic wave

Is it possible to create an electromagnetic wave of near zero frequency? An electromagnetic wave carries energy. If we can make the frequency of an EM wave vanishingly small and make it practicality ...
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### Why monochromatic waves exist even theoretically

I was reading this question. Where the author made a statement that If I take a wave with period T, it is also true that it has a period 2T, 3T and so on. That is, it has frequencies of 2π/T, but ...
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### why does the frequency of a wave remain constant?

They say the frequency of a wave is its fundamental character, thus remain constant throughout its propagation regardless the medium through which it travels. Could anyone explain why frequency of ...
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### Why are FM radio waves less susuceptible to interference than AM? [duplicate]

When studying modulation of radio waves (or of most electromagnetic waves for that matter) I came across that question. Why are FM waves less susceptible to interference than AM waves? I know that in ...
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### Is there any solution manual to A.P. French's 'Vibrations and Waves'?

I'm trying to work through A.P. French's Vibrations and Waves. Unfortunately, I can't check the details of my solutions since the solutions aren't given with the textbook. Does someone know where I ...
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### Reason for absorbance

First quoting the example which raised my curiosity"when light passes through polaroid it absorbs certain direction light rays" My question is how this phenomenon of absorbance occurs is this some ...
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### Why do we hear a different timbre when someone speaks with helium (or other gases) in their lungs?

Let me make one thing clear: I am fully aware that the change in timbre comes from the change in acoustic wave speed when going through a different medium (just like light). However, would I not ...
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### Fresnel zone with different antenna heights

I've looked at the formula to calculate the first Fresnel Zone: $$r=17.31 * \sqrt{\frac{d_1*d_2}{f*d}}$$ whereby $d_1$ and $d_2$ are distances from the obstacle to the link end points in meters, $r$ ...
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### Will phase change occur in the formation of standing waves?

I have learned that standing waves are formed by two waves overlapping with each other where the two waves are the same in wavelength, frequency, and amplitude. I have a doubt in how the phase of ...
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### Explanation of sounds waves and speed.

When a rocket is traveling toward a mountain at 100 m/s, the sound waves from this rocket's engine approach the mountain at speed V. If the rocket doubles its speed to 200 m/s, the sound waves from ...
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### Direction of momentum given by the de Broglie relation

The momentum of an electron can be computed by the well-known classical mechanics equation: $p=mv$ where $m$ is the mass of an electron, and $v$ is its velocity. In this case, since $v$ is a vector,...
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### Can localized fluid perturbations be accelerated by pressure gradients?

I would like to know if there are any examples in fluid dynamics (or continuum dynamics) of small perturbations (or waves, solitons, or other "localized" solutions of the fluid) being accelerated in ...
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### Which arrangement of pipe and sources can create a standing wave?

A loudspeaker emitting sound of frequency f is placed at the open end of a pipe of length l which is closed at the other end. A standing wave is set up in the pipe. A series of pipes are then set up ...
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### Independence of Period and Amplitude in Simple Harmonic Motion

In Simple Harmonic Motion, the period $T$ of an oscillation, is said to be independent of the amplitude $A$ of an oscillation, but why is that so? Attempting to derive from the equations of Simple ...
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### Why do we add intensities for coherent sound sources?

When there are N coherent sound sources playing the same note at equal loudness, their sound waves add up to make a sine wave of the same frequency but most likely different amplitude (can be anything ...
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### Standing waves: why do 2 standing waves don't cancel each other?

I have learned that when two waves are combined, the peaks and troughs could be in the same direction (so that means the amplitude is increased) or the peaks and troughs could be in the opposite ...
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### How are sound waves of different speeds heard differently?

Lets say that there are two waves. They are both identical in every way except that one is traveling through a gas and another through a liquid. As we know they are traveling at different speeds and ...
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### Are light waves sinusoidal functions?

I was researching sinusoidal functions when I realized that the wave produced by a wave function looks exactly the same as a light wave. Is a light wave a sinusoidal wave, and can a light wave be ...
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### why cannot longitudinal waves travel through space (vacuum)

'The reason sound can't travel through a vacuum is that sound needs a medium (solid, liquid or gas with real vibrating molecules) and not because it is a longitudinal wave' How does this make sense as ...
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### What is y(x,t) = Acos(kx - wt)? [closed]

Im very new to wave mechanics and I've come across the following wave equation. I know this is asking too much,but I wanted to know what is the significance of this equation? what does it tell us / ...
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### Does a reflected evanescent wave grow in amplitude?

When considering an evanescent wave travelling in a region between two regions where the solution takes the form of a travelling wave from the maths we have a forwards travelling wave that decreases ...
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### 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. ...
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### 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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### 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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### 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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### 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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### 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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### 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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### 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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### 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 ...
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### Why does increasing distance from the double slit in Young's experiment increase the separation between the fringe pattern?

I don't understand what equation deals with this.
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### 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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### 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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### 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 ...
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### How can I prove that antinodes are present at both open ends of organ pipe mathematically? [on hold]

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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### 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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### 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 ...