# Questions tagged [waves]

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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### Why temporal and spatial term is multiplied to get the wave equation?

When deriving the wave equation we have: $$y_{spatial} = A\exp(ikx)$$ $$y_{temporal} = A\exp(-i\omega t).$$ Then the overall wave equation is obtained by multiplying both time and spatial component. ...
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### Types of Mechanical Waves

When knocking on a door, does that create a transverse wave or a longitudinal wave? I know it's one of these mechanical waves, but which one?
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### - The minimum distance at which a radar can detect a target is 270 m. Determine the wavelength at which the radar operates if it emits pulses, [closed]

The minimum distance at which the radar can detect a target is 270 m. Determine the length of the waves at which the radar operates if it emits pulses, each of which contains 6,000 electromagnetic ...
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### Is sound essentially motion?

From my understanding, the only way for humans to create sound is by moving our bodies, vocal cords, or by moving other objects. So depending on how fast we or other objects can move, different ...
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### Confusion regarding structure of standing waves in organ pipes in non standard cases [closed]

In a resonance tube, resonating frequencies occur at l1 and l2 (suppose). Then how will the standing wave look like when l1<l<l2? And when does a standing wave with different loop length get ...
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### How do I find the reflection coefficient related to the lumped impedances? [closed]

I am having a hard time dealing with lumped impedance in problems related to traveling waves. How can I handle problems where both characteristic impedance and lumped impedance are present, as in the ...
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### How is symmetry boundary condition related to reflection of a plane wave from a rigid flat surface?

My question is in in the context of "method of images" when applied to an incoming incident acoustic pr plane wave. For a flat rigid surface in $XY$ system, the surface (positioned at $Y=0$) ...
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### If you are on the moon, would you be able to hear your hands clapping if you're not wearing your spacesuits?

As I understand it, sound needs a medium to travel and more often than not, the medium is the atmosphere, however sound can also travel through solid objects. And even we can hear our own voice ...
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### Could the double slit experiment demonstrate not that particles behave like waves, but that together particles behave as a wave? [closed]

Clearly particles individually pass through slits, be it a single or a double slit experiment. The fact that wave interference is evident in their trajectory may be due to their interaction upon ...
1 vote
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### How can I find if it is gold or lead with waves? [closed]

I would find if a bowl is made of lead or gold know freqencies $w_{1}$ and $w_{2}$ and a vibrator induces waves at $z=0$ (and there are reflected waves). I do it with progressive plane electromagnetic ...
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### What is the amplitude in c) part and why is the phase difference not $\pi$? [closed]

So this is from OCW First part is fairly easy natural frequency comes out to be 10 Hertz,Gamma came out to be 1/2 for two traffic signals and 1 for a single traffic signal, In second part I am ...
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### Can a standing wave indistinguishable from a travelling wave for a stationary observer?

Say that you place an observer at a point in space where the non-zero amplitude of a standing soundwave is equal to the amplitude of some travelling soundwave (that is, the two opposing travelling ...
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### Is it not possible for true standing waves to appear in nature?

From what I understand, standing waves form when the following conditions are met: 2 waves of equal frequency, amplitude, and polarization are travelling in opposite directions. So if any of those ...
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### Difference between structural acoustics and flow induced acoustics

I'm researching about sound induced inside water pipe and came up with some questions. For numerical acoustic calculation, I found two ways. Using acoustic analogy such as Lighthill equation or ...
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### Phase Angle: AC Circuit

I am seeing this everywhere when I look up impedance and reactance for AC circuits. Below is a picture below from the website here. They say the formula for the phase angle is $y=\sin(\omega t+\phi)$....
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### Paraxial Spherical wave emanating from point source

I'm reading through chapter 5.3.1(Impulse response of a Positive lens), in Goodman's "Fourier Optics"(p.109). An object is placed a distance $z_1$ in front of a lens. If we place a point ...
1 vote
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### Two-Ray Ground-Reflection Model: Understanding the Difference in Phase Offsets at the Receiver

Currently, I'm trying to understand the Two-Ray Ground-Reflection Model. During my research, I came across the following simplification expressing the received power as follows (taken from Wikipedia): ...
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### Is the argument of the $\sin$ function for a monochromatic plane wave dimensionless?

I was looking at the following representation of a monochromatic plane wave: $$F(\vec x, t) = A\sin(2\pi\nu(\vec x \cdot \hat n - ct) + \phi)$$ but, upon analyzing the argument of the sin function, ...
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### On sum of amplitudes in Wave Mechanics

Consider Schroedinger equation, which I write in the form $$(\mathscr{L}+V)\psi=0$$where $\mathscr{L}$ is the kinetic and time-derivative operator. Now, imagine I have two point sources 1,2 with ...
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### How do the forces involved in EMR continue to occilate past emmision of a photon

If electric fields are created by an accelerated charged particle, such as an electron, and magnetic fields are generated by electric fields in motion, what are the individual fields that make up ...
1 vote
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### What is the relevant phenomenon behind Undulatus/Radiatus cloud formations?

I am seeing many people claiming that cumulus clouds that sometimes form periodic wavy patterns (see images for "altocumulus undulatus" or "Radiatus" for instance) have no ...
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### What is an electromagnetic wave exactly?

This question might be very silly, but I am really confused about it from several days. Look transverse waves on a string propagate along the string due to the electromagnetic (EM) forces between ...
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### Why the consecutive spherical wavefronts produced by a rest point source are not equidistant? [closed]

I learnt that a point source produces spherical wavefronts and i know the reasoning behind that too and while studying the concept again a question popped in my mind, that "Are those spherical ...
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### Derivative of displacement in deriving expression for intensity of sound waves

I am currently working on deriving the expression for intensity of a sound wave: https://openstax.org/books/university-physics-volume-1/pages/17-3-sound-intensity The previously mentioned book states: ...