Questions tagged [doppler-effect]
The Doppler effect refers to change in the observed frequency of a wave if the observer and source are in relative motion.
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Is there a Doppler effect on the surface of an expanding balloon?
Imagine a stationary transmitter which vibrates the surface of the balloon and a stationary receiver half way around the balloon that can pick up these waves. Let the balloon expand. Will the ...
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Optical path length for sound
The definition of optical path length is the distance that light could have travelled in the same time, in vacuum. So, can we define something analogous for sound waves, like an "acoustical path ...
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Does the Doppler effect change frequency?
Would a high-pitched unhearable frequency be heard whilst the doppler effect is in play?
For example, when a car uses its horn whilst travelling by, the pitch shifts as it passes - which is the ...
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Maths behind red/blue-shifting [closed]
I watched this video of silly science facts, on of which stated "you can avoid red lights by travelling at around 114,000,000mph (51,000,000m/s) because the red light would be blue shited enough ...
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Analytical Solution of Sound Wave Propagation in Moving Medium (1D Problem)
I am trying to use frequency-wavenumber analysis to estimate sound wave propagation in a moving medium (fluid). I need to test the technique on analytical data. I wonder if there is an analytical ...
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Doppler shift in De Broglie's wavelength
If I were to take a particle, moving at a non relativistic velocity, it will have a wavelength (according to De Broglie). However, If I were to change the referance frame of the motion, I know that ...
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Doppler effect with a moving observer [duplicate]
I have seen the doppler effect derived quite a few times when the observer is moving. What is the source is also moving at some random velocity in some angle?
How would one go about thinking about ...
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Doppler Cooling Limit
Can anyone help me understand this simple passage on Christopher Foot (Pg.189, Eq.9.24) about Doppler cooling:
$\frac{1}{2}M\frac{d\bar{v_{z}^{2}}}{dt} = (1+\eta)E_r(2R_{Scatt})-\sigma\bar{v_{z}^{2}}$
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Photon Doppler shift and Lorentz invariance
My understanding is that the energy of a photon depends your your reference frame because the energy of a photon depends on its frequency and its frequency may get Doppler shifted. Now, I am trying to ...
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Doppler shift of light as seen by a free falling observer towards a single star [duplicate]
Consider an observer who is free-falling towards a star with no angular momentum (radial movement only considered). The velocity of the observer equals the escape velocity at each distance, but in ...
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Violation of energy conservation: cosmological Doppler-effect in what might seem an inertial frame of reference
I've seen disagreement about whether the cosmological Doppler-effect violates conservation of energy. It can be complicated to analyze since there is no reference frame of a photon.
My question is: ...
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Was doppler effect for light proven experimentally?
If so, provide me with the data sources. From what I read, doppler for light is taken for granted. Or sometimes based on theoretical formulas. But if one wants to theorise, light is a mix of photons ...
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Low intensity EM waves and doppler effect in Thomson Scattering
We know that when the wave model of light was being used in physics there was Thomson Scattering Model to explain the interaction between a free electron and a light.
The Thomson Scattering was ...
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Light wave/photon doppler effect
So I understand the explanation/derivation of doppler effect from the perspective of wave crests emission being stretched out as the source moves. But how does this work from the photon point of view?
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Methods for calculating the orbital speed of a star in a binary system
As I understand it, to calculate the speed of rotation of a star in a binary system that is receeding, that is in the same plane as us (inclined at 0 degrees) the method is use the Doppler formula: Δλ/...
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(SPOILER: Big Bang Theory) How does this shirt Sheldon wearing, depict the Doppler effect?
This image of Sheldon wearing the shirt is from Season 1 Episode 6 of the Big Bang Theory sitcom.
He goes on to demonstrate the Doppler Effect. But I don't see it. I tried thinking of it as a ...
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Large wavelength moving very fast or smaller wavelength moving slow
I was reading a book, which derives the final frequency due to doppler effect for sound.
It states
...if the source is moving, the effective wavelength of sound will be changed...
$$f' = f\left(\frac{...
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Symmetry and Doppler
If relativity is symmetrical (triplets moving away and returning to the center) then what happens to the Doppler effect as seen by the moving triplets?
A B C
A should see C moving (Doppler) away/to ...
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What happens if you're on a spaceship accelerating close to the speed of light, but then stop accelerating?
So most people want to ask what happens if you go super-close to the speed of light and try to go a bit faster. I want to know what happens if you stop accelerating at close to $.99c$. Not decelerate, ...
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Is the amplitude of a wave affected by the Doppler effect?
When I search on this question online, I get conflicting answers. Most sites will tell you that the amplitude is not affected by the doppler shift, but in Einstein’s 1905 publication on special ...
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Doppler effect in QED
I am currently learning the basics of quantum electrodynamics. As I was reading through my book of choice on the subject (The Quantum Theory of Light, by Rodney Loudon), it occurred to me that it ...
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Is there a Doppler effect measured on the sunlight depending of the seasonal position of the Earth regarding the motion of the Sun through space?
The whole question is mentioned in the title but here I would add the conjecture that I am affraid that the answer(s) should be similar to a possible question about Michelson and Morley experiment...
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Do the Doppler Effect and EM Stress-Energy Tensor Imply An Object's Emitted Light Exerts More Gravity Upon You When You Are Moving Towards It? [closed]
(Please message me or comment if this is not concise enough as a question)
GIVEN:
Energy in the form of electromagnetic waves (aka photons) exerts a gravitational force proportional to said energy:
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Doppler effect on intensity of sound wave [duplicate]
The intensity of a sound wave is dependent upon pressure amplitude squared.
Consider a source of power P emitting sound in all directions. An observer moving with a speed v towards the source will not ...
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Relativistic equation for the Doppler effect
From Robert Resnick's "Introduction to Special Relativity", the frequencies in two different inertial frames as shown below,
are related by
$$f = f'\frac{1+\beta \cos\theta'}{\sqrt{1-\beta^...
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Why do we cool atoms with laser light opposed to normal light?
When we use laser light to cool atoms, we get into some problems, because when atom beam slows down the Doppler shift changes the frequency of light in atom's frame of reference, so they can't ...
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Doppler effect with and without varying intensity of sound? [duplicate]
Take the classical example of fast moving Car whizzing past you.
You hear the .....oooooooOOooooooo.....
sound.
But in that case most of the effect we are observing is the change in intensity of sound....
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Reflection vs repeater color shift
So, my question is: what (if any) difference is there in color shift for an EM wave being reflected or being repeated in a moving reference frame?
My common sense tells me there ought to be no ...
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Relativistic Doppler effect and COE
I admit I am confused and at this point pretty clueless with what's going on so I apologise if the following paragraphs sound messy.
So here's what I know (but could just as well be wrong)
$E = hf$, ...
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Does the Doppler effect work either way?
I know that the Doppler effect is when waves get compressed or stretched. For light this causes red shifts and blue shifts. My question is if we were moving towards or away from the source of light, ...
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How would the Redshift of a Photon be influenced if it travels through a volumetric gas disk?
so me and a buddy have been working on a Black Hole render engine for quiet a while now. And at this point we have most of the technical stuff worked out. Which results in images like these;
Note, ...
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How do we deal with doppler effect in $3D$ space?
In $2D$ it's easy to deal with doppler effect given the velocity of the source and the velocity of the observer like in fig (1) where we have the observer at A static and the source in direction of $\...
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How to interpret the velocity from relativistic Doppler effect/equation for the redshift of cosmic background radiation? [closed]
This question has a moderation and downvotes issue: One of moderators keeps deleting one last single comment with the crucial piece of information, that clearly explains, why the given answer is wrong
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Twin Paradox doppler resolution
I've been doing some doppler thought experiment around the twin paradox,
(wikipedia)
The paradox centers on the contention that, in relativity, either twin could regard the other as the traveler, in ...
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Doppler effect on bistatic system with offset sensors
I am wondering if there would be any induced doppler-effects for a setup where a object is moving in a straight line but the emitting and receiving sensor are offset. The equation for the bistatic ...
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Special relativity effects in rotational reference frame
If I am sitting in the rotational reference frame, it is very easy to get some objects moving with the speed of light in relation to me. For example, the average distance to the Moon is 384400 km. If ...
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How distance is determined between two inertial frames in empty space using Bondi’s radar method?
I have read how Bondi’s radar method can be used between two vessels in empty space to determine their relative distance and also if their distance is increasing or decreasing.
Can Bondi's radar ...
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What is the coordinate-free expression for doppler effect?
I'm interested in the general formula in terms of a position vector velocity and inner products, without reference to any coordinates.
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Finding rate of change of the distance from an observer on earth to a satellite in orbit
This is a satellite motion related question. To give context, imagine a satellite orbiting Earth at a distance 'R' from the center of the Earth at constant velocity 'v'. An observer on the surface of ...
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Question regarding the Doppler Effect in a binary star system
I was studying Doppler effect and could not understand the effect of Doppler effect in the following systems.
In the above system the book says the doppler shift is zero
However in this system there ...
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Proof of double Doppler shift
We know that the Doppler effect for EM radiation is $\Delta$$f$ = $\frac{v}{c}$$f_0$
$\Delta$$f$ = the change in frequency
v = the relative speed of the source and observer
c = the speed of light in a ...
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How does the echo of a radio wave from Venus depend on the rotation speed and direction of the planet?
In this paper from around 1960 scientist used echos of radio waves from the Venus' surface to determine its rotational speed and direction. How can the rotation of Venus affects the echo of the radio ...
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Was Lewis Epstein right to dismiss explanations of relativity that are based on signal delay?
Ever since reading Relativity Visualized by Lewis Epstein, I believed that signal delay is not the explanation for relativistic effects. Here's a quote from the book:
"Suppose a pair of stars (or ...
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Reality vs Doppler calculations
I just tried to explain Doppler and found a mismatch between by calculations and real world experience. I took a case of an ambulance approaching a listener going 67 mph (30 meters/sec) emitting a ...
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Confusion with Doppler effect problem
A detector recedes from a stationary source of sound with a speed that increases continuously and without any limit. Describe qualitatively, the frequency of sound detected by the detector. Assume ...
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Is the frequency of photon invariant?
I saw a stackexchange answer that says the energy of photons is dependent on the reference frame. I did some digging and found that this is because the frequency of photons is dependent on the ...
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What is wrong with this derivation of the Special Relativity Doppler Shift formula?
I tried to use the Lorentz coordinate transformation between two inertial frames to generate the Doppler Shift formula, but I ended up with $\lambda$ over $\lambda'$ upside-down. I must have a ...
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Is it possible to determine the distance between the earth and a star by only studying the light emitted from this star?
I was reading about the Doppler shift and how we can measure how fast something is moving through its Doppler shift. This got me thinking is their a way/formula to measure the distance between us and ...
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Relativistic Doppler formula at high speed
I believe this is a simple question, but I cannot find the answer anywhere. According to the relativistic Doppler formula, the emitted ($\nu_{\text{em}}$) and observed ($\nu_{\text{obs}}$) frequencies ...
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Doppler cooling before sideband cooling
I've seen that Doppler cooling is used to cool down the system before performing sideband cooling. I have 2 questions about it.
First, why do we need the system to be cooled before performing sideband ...
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