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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How to calculate doppler shift in mobile communication system?

I want to know how the following equation comes from. $$f_D=\frac{1}{2\pi} \frac{\Delta\phi}{\Delta t}=\frac{v}{\lambda}\cos\theta$$ The picture above is drawn by me in mspaint (sorry for bad ...
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According to the doppler effect , if my source is faster than sound , will I hear the sound backwards? [duplicate]

In a hypothetical situation,say I have a sound box with a very large volume and let's say it is placed pretty far away from me. If it travels towards me at a speed higher than that of sound in the ...
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Is the rate of light emissions actually the frequency of the light?

I am confusing with the concept of frequency in the context of Doppler effect studying SR. The Schutz says, if the source emits pulses more frequently, then the observer would see the lights not only ...
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Doppler shift of light from stars and galaxies [duplicate]

I was reading about how we can ascertain whether a cosmic object is receding from or approaching us by studying the doppler shift of its spectrum- I mean the redshift and blue-shift. But we have no ...
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54 views

Can Doppler Shift be used to calculate speed of an observed object?

Thanks for looking. Just musing over an idea this afternoon: if I had a radio controlled plane, I could obviously calculate its airspeed based on pings and the known speed of sound if it was ...
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How'd you explain Red shift and Blue shift with respect to Doppler Effect

I understand Doppler effect in Sound and Water because there we can observe relative speeds. But in case of light, the speed is same in all references so is the change in relative wavelength due to ...
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42 views

Time-dependent time dilation for circular orbits around a Schwarzschild black hole?

Take two clocks, one in a circular orbit around a Schwarzschild black hole and another with a distant observer. The time dilation factor between the two clocks is said (at ...
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25 views

How can the angle to a pulsar be determined by measuring its redshift?

Suppose we (a spacecraft, probe, or similar) know our location only to within a few billion km (a few Tm) in any direction in 3D space, and we want to determine our location to a higher degree of ...
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Doppler: how to derive formule “source moving” from formule “observer moving”

A question like this has already been asked, with a satisfying explication (the relative motion of the source and the observer with respect to the medium (air) is different), but without a derivation ...
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What are the limitations of velocity selective coherent population trapping?

I'm somewhat familiar with limitations of Doppler cooling, particularly with the one photon recoil limit, but what I was curious about was what is the next barrier to cooling approaching absolute ...
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Ultrasonic Transducer Spacing

Given a SCH 40 steel pipe of diameter D and length L, what is the proper spacing for ultrasonic transducers in a Doppler Shift setup assuming the transducers are angled at 45 degrees? The reason for ...
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Curious question about light and photons

If a photon wavelength (e.g., yellow) is isolated from the other wavelengths that the sun emits (once it gets to earth), can that particular particle/photon be distorted slightly into a wavelength ...
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Is absorption imaging in ultracold gases (BEC) a method destructive of the system?

As of title, I wonder whether this imaging method heats the gas up to the loss of quantum coherence. Let's consider a specific example, a gas of 87Rb (Rubidium) and its D2 line. I might be wrong in ...
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61 views

Is there a doppler effect on the images of stars around rotating black holes?

I'm an illustrator working on a project involving rotating black holes like those discussed in "Gravitational Lensing by Spinning Black Holes in Astrophysics, and in the Movie Interstellar" by James, ...
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1answer
34 views

Coulomb excitation of a heavy nucleus

In Coulomb excitation measurements involving a stationary target getting excited, why do the de-excitation $\gamma$-rays get Doppler shifted and Doppler broadened as well? How can these be corrected ...
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122 views

Redshift of distant galaxies: why not a doppler effect?

How can I explain to my 17 year old pupils that the observed redshift of distant galaxies cannot be interpreted as a doppler effect and inescapably leads to the conclusion that space itself is ...
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1answer
57 views

How to explain Doppler redshift of light?

For other waves like water or sound, it is easy to understand Doppler effect, because for those waves, the speed of wave in different inertia reference frames changes. But for light wave, the speed ...
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95 views

Does a spaceship travelling at near lightspeed see the universe aging slow or fast?

Now I know this probably is well trodden territory, but this question has bugged me for some time, and I couldn't find a similar question in the archives (although plenty about relativistic time ...
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67 views

When a photon escapes a black hole, why is it red shifted? [duplicate]

I think that is how astronomers hunt for these elusive objects using radio telescope and also gravitational lensing, I'm wondering how these photons lose their energy while encountering black hole or ...
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42 views

Time domain representation of a waveform from an accelerating source (doppler effect)

Consider the scenario where a stationary observer observes a source moving in 3 dimensions, emitting a signal $s(t)$. I would assume only the distance between the source and the observer, $x(t)$, has ...
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220 views

Doppler effect of matter waves

We all know that the relativistic mass of a moving object in Special relativity increases for an observer who is measuring it for a moving object. We also know the the concept of particle-wave ...
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39 views

Crest in Light Doppler Effect

The way it is explained in wiki Doppler effect in sound happens because waves of particles with biggest density called crest hits our eardrums more often if object is moving towards us (increased ...
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1answer
87 views

Bouncing sound off a wall

Let's say I am moving at a velocity $v$ away from a wall, and emitting a sound toward a wall. Is it true that I hear the sound at the same frequency that I emit it?
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153 views

Influence of acceleration in acoustic doppler's effect experiment

Recently I've done an acoustic doppler's effect experiment for physics lab assignment. The setup was two microphones in a straight line, movable object with sound source and a pc with the usual sound ...
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126 views

Is the amplitude proportional to frequency in electromagnetic waves?

In Einstein's 1905 paper, under the section: § 7. Theory of Doppler’s Principle and of Aberration Einstein derived the relativistic Doppler effect: $$f'=f\dfrac{1-\cos\phi \cdot ...
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96 views

How is the speed in Hubble's law determined, if not from the Doppler shift?

Hubble's law originally mentions the speed (i.e. proper motion) of a receding galaxy, as calculated via the Doppler effect from the observed redshift. However, the observed redshift is today explained ...
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107 views

Doppler shift from a transversely moving plane mirror

Below is the diagram of the question I have on the Doppler shift of a light emitted from a stationary light source $S$ at an angle $\theta_1$ toward a transversely moving plane mirror $O$ having ...
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265 views

What are the characteristics of light entering a disk spinning at near $c$?

If I were to spin a translucent disk so that the edge is spinning at .9c and shoot a laser beam at it perpendicular to the edge, what would happen to the light as it travels in one end of the disc and ...
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Is there a standard of rest in the universe? [duplicate]

If you measure the cosmic background radiation you will find that in any direction it is roughly the same. However, if you were to travel near the speed of light relative to the Earth in a particular ...
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1answer
88 views

How large or small can frequency in the EM spectrum get?

The largest frequency range is gamma rays, but does the EM spectrum 'stop' somewhere? Like is there a limit to how large a frequency can get? Or how small frequency can get? Is it one of those things ...
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43 views

Hearing sound when going supersonic

Suppose we are travelling supersonic along a straight line. Further up along the line, there is a stereo, that's emitting sound at a frequency that changes in such a way that the Doppler shift caused ...
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1answer
41 views

Doppler-shift of AC-electricity

A tram is powered by overhead wire, the wire has alternating voltage of 1000 V RMS, the frequency of the alternating voltage is 50 Hz. The rails are the other wire. The tram is moving at speed 100 ...
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1answer
218 views

What does the ratio $\frac{x-ct}{x'-ct'}$ signify?

$(x,t)$ being coordinates of any event in an inertial frame $A$ and $(x',t')$ being the coordinates of the same event in another frame moving with uniform velocity $v$ along the same direction in ...
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81 views

Is an infinite Doppler effect plausible?

When I was young (which I still am) I was amazed by the sound jet fighters make when they break the sound barrier - a sound similar to an explosion which caused my school to shake. Later I learned on ...
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Where does the energy go when light is redshifted? [duplicate]

Imagine a galaxy millions of lightyears away and, obeying Hubble's law, moving very quickly away from us. Now imagine the same galaxy emitted a green photon in our direction (a photon with a ...
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136 views

doppler effect in sound waves

While studying doppler effect we study that as the locomotive banging up the horn is moving the produced waves come closer, making wavelength decrease and frequency increase ,and so is the wave heard ...
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206 views

Sounds of supersonic objects

Would you, as a stationary observer, hear a sound in reverse when the source of the sound travels with twice the speed of sound? Of course, he wouldn't hear anything at all before the airplane passed ...
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74 views

Is it possible for the light (photons) to turns into normal electromagnetic signal?

I want a theoretical opinion about this question: The relativistic Doppler Shift equation for the light is $$\frac{f_s}{f_o}=\sqrt{\frac{1+\beta}{1-\beta}}$$ where $\beta=v/c$ is the velocity of the ...
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What happens to sound at speeds greater than mach 1? [duplicate]

We know that a moving source of sound waves produces Doppler shift, so that sound waves are closer-together in the front and farther apart behind, creating a difference in pitch. Let's consider a ...
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104 views

What is the doppler (frequency) shift called in the time domain

Almost all descriptions of the 'Doppler shift' are with reference to the change in frequency of a regular sinusoid or pulse train. What would be the appropriate term (for the same base physics ...
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Why doesn't the motion of a car affect the frequency of radio stations?

When we go in a car and tune to an FM radio station, why doesn't our motion disturb the frequency? Like the Doppler effect?
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'Doppler redshift' Vs 'Cosmological redshift'

It is not difficult to understand the differences between 'Doppler redshift' and 'Cosmological redshift' conceptually. But how do astronomers distinguish them when doing observations?
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Calculating frequency of sound when source is moving faster than the sound waves

I have used the Doppler effect relations to calculate the frequency of the sound of an object that is moving faster than the speed of sound, by using this formula: $frequency = ...
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Is redshift possible if relative speed is 0?

Since we are in a galaxy that is moving 1M mph, and the speed of light is constant, is redshift affected by whether you are facing toward or away from the direction the galaxy is moving? Suppose you ...
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133 views

Perpendicular doppler effect photons

If I have a photon with frequency f in the lab frame and the observe it in a inertial frame moving perpendicular to the photon. The direction of the velocity of the photon must change but does this ...
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104 views

How fast would you have to go to claim you saw the red light as green due to the Doppler Effect?

Driving toward it, I suspect you would have to be going at relativistic speeds. Calculating this, it appears to be around 1/6 the speed of light when driving directly at it, but since you are on the ...
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Is it possible to derive the Doppler effect formulas for sound using relative velocity?

Is it possible to derive the Doppler effect formulas for sound using relative velocity? If possible can anyone please explain it to me.
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1answer
61 views

Conservation of Energy in Blue Shift

Imagine light coming down and hitting a neutron star. It light is blue-shifted. I know that energy/mass is conserved and that the energy to blue-shift it comes from the gravitational field, but how is ...
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Is there any way to differentiate between a redshift caused by recessional motion vs. gravity?

How certain, if at all, are astronomers that the redshift they are measuring is relating to recessional motion as opposed to gravity?
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Can anything other than recessional motion cause a redshift?

The question pretty much says it all. Is there any force, or circumstance, or anything that we know of that can affect the measurement of a red shift?