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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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Which type of redshift does the equation $\Delta \lambda / \lambda = v/c$ apply to?

Which type of redshift does the equation: $$\Delta \lambda / \lambda = v/c$$ apply to, that which results from the Doppler effect, or that which results from cosmological expansion? Does it even ...
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What relations between sound frequencies of a sound wave in motion that gets reflected from the wall occur?

Let's say you're driving forward by car and when you press the horn, the sound is reflected from the building in front of us. If we mark the frequency of the sound sent by $f_1$, frequency of the ...
41 views

Why does the frequency of a wave change in the Doppler effect if it is a property of the source?

If the frequency of a wave is the property of the source emitting the wave, the number of times it vibrates per second, why does the frequency of an approaching or a receding ambulance or train change ...
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Is there a near zone inverse Doppler shift?

Engheta et al. found such an effect in free space in 1980, published as On the Near-Zone Inverse Doppler Effect August 1980 IEEE Transactions on Antennas and Propagation 28(4) Yehuda Ben-...
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How to interpret doppler curve images of Chandrayaan-2 lander?

The frequency transmission data for Vikram, lander of Chandrayaan-2, received by 25 meter Dwingeloo radio telescope is plotted and tweeted by Cees Bassa. Kinks in the Doppler curve are interpreted as ...
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How to calculate tube flow in layered ultrasound phantom using Doppler

Using a tank with the top filled with water and the bottom filled with a gel which is slightly denser than the water. Inside the gel is a tube tilted 60 degrees above the horizontal axis. The tube ...
124 views

Images traveling faster than light

Please help me understand my mistake(s) in this reasoning. I will write as if I knew exactly what I'm talking about for the sake of clarity, but I of course don't. Consider observer A and its ...
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Transverse Relativistic Doppler effect in Non-inertial reference frame

If I have a Non-inertial reference frame in Earth (rotating camera or just my rotating head with eyes) and I am watching the Moon. If my Non-inertial reference frame in Earth rotating with the speed ...
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Changing the refractive index of biological tissue using Radio Frequency (RF)

I have been looking into changing the refractive index of a specific medium initially using Ultrasound in a known location via a mechanical Doppler shift of the emitter (Mahan et al., 1998) which has ...
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Changing the refractive index of a specific medium using radio frequency (RF) waves

Using Ultrasound one can change the refractive index of a specific medium such as biological tissue, I was wondering if it is possible to change the refractive index of a medium such as biological ...
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Doppler effect of light

Doppler effect for light is created for relative motion . But shouldn't light always approach us at the same velocity 'c' regardless of the relative speed ?Then how does Doppler effect work ?
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Problem with the derivation of the Doppler broadening of atoms spectral lines

I have a problem with the derivation of the gaussian behavior of the doppler broadening of gas atoms specrtal lines. I will describe what I have done so the problem along the derivation could be ...
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Relativistic Doppler Effect between rotating bodies

The Wikipedia article "Relativistic Doppler effect - One object in circular motion around the other" confused me. There they say that when the light source orbits the observer, the observation of ...
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Why are there so many Doppler Effect formulas?

I was just introduced at my class, a phenomenon, known as the doppler effect, where the observed frequency increases as the source/observer approaches each other, but decreases, if they were moving ...
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Do photons exchange energy with objects according to their momentum?

I've been thinking about the doppler effect, where electromagnetic radiation experiences a redshift if the radiation source is relatively moving away from the observation point, and a blueshift if it'...
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Why is relativistic beaming/ Doppler beaming occur at non-relativistic speeds

The reflexive motion of a binary star system causes the host star to occasionally wobble towards and away from an observer on Earth, which gives rise to an effect called relativistic beaming. This is ...
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Relativistic beaming/ Aberration effect derivation

I'm researching applications of relativistic beaming and I want to derive a formula for the aberration effect but I am stuck (I am off by a factor of 1/c). Here's what I have: Consider a star in its ...
25 views

Apparend frequency when the source travels with the speed of sound

Let's assume an object travels with the speed of sound towards a stationary observer in a straight line. Let's say the frequency emitted by the jet is $f,$ speed of sound is $u.$ and the speed of jet ...
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Doppler shift moving parallel to wall [closed]

Suppose you are screaming and running in an area parallel to a wall. What would be the frequency you hear considering that you are getting away from the part you've passed and getting close the parts ...
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Relativistic Aberration Formula Derivation: looking for a hint

The literature on relativistic beaming / doppler beaming is scarce, so I hope the community can shed some "light" on this topic. I want to derive a formula for the phenomenon known as relativistic ...
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Detecting phase shift

Points A,B,C lie equidistant on a straight line. There is a medium streaming from A to C. Thus, if a continuous sound is emitted at B, it will arrive at A with a slight phase shift relative to the ...
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Is the expansion of the universe uniform? Are there parts which are expanding faster than others?

Is the expansion of the universe uniform? Are there parts which are expanding faster than others? The very fabric of the universe is expanding..but is it expanding at a constant rate? If it is not ...
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Problem with wind (Doppler Effect)

Mi physics book has a problem that states The C note has a frequency $\nu=261,6$Hz. In an open concert wind blows from the stage to the audience vith speed $v_o=6m/s$.What is thefrequency heard by ...
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Relativistic Doppler Effect from source’s frame

Could someone please help me understand the derivation of the relativistic Doppler effect of light for objects moving away as derived from the source's reference frame? There’s no problem for me to ...
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Relativistic doppler efect

I got a little confused with the derivation of doppler effect for light as showed on wikipedia. The derivation states that when the source of light and the receiver are moving away from one another, ...
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Does the Doppler effect happen instantly?

Assume that a far star sends light toward a receiver. If we move this antenna such that it accelerate first for a moment, and then it moves with constant speed, we can see that the frequency of the ...
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How are the time dilation and the relativistic Doppler shift added together in what observers “see”?

I'm using the illustration from this question: Suppose A and B are d light years away, and at rest. Then they symmetrically start to travel toward each other (symmetric acceleration process in ...
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Black hole, gravitational redshift, Doppler effect

I'm studying up on the physics around black holes and got myself confused with the concepts of gravitational redship and Doppler effect. Imagine a spacecraft orbiting a non-spinning black hole. It ...
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Could ultrasound pings and triangulation really help de-scatter diffuse red light for imaging?

Does the science explanation in the latest OpenWater TED talk make sense in principle? The claim involves taking advantage of the doppler effect. Could someone give a more detailed explanation as to ...
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Doppler effect in sound

In Doppler effect for sound formula we consider the velocity of source and observer w.r.t. medium but just what about velocity of sound it should also be w.r.t medium right? If the medium is moving ...
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Issue deriving observed period of a moving signal in different reference frames

Consider a receiver on Earth measuring radio waves from an incoming slow moving UFO. Here is my attempt to find the period of the signal as measured by the earth observer. T' is the period of the ...
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Speed of a video and Doppler effect

While watching videos at 1.5x or 2x the original speed I often notice a change in the speaker's voice. I am not sure if that is a change in pitch or something else, and was thinking how it could ...
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Relativistic Doppler shift of gamma photons - paradox

My question is related to this older question at stackexchange - physics. How much energy a photon needs to create a black hole ? My question: How close to the speed of light a gamma photon ...
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Why does the black hole's matter ring in the image released on April 10th seem to lack blue/red shift? [duplicate]

If the matter around a black hole is spinning around it at nearly the speed of light, then the blue/red shift on each side should be quite visible (even though we're watching at an angle). But in this ...
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Relativistic doppler effect vs Gravitational Redshift

I recently found a pretty unknown but remarkably clear and simple article (Cochran, 1989) on different doppler shift relationships for an uniformly accelerated observer in a 1+1D flat spacetime, using ...
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Apparent frequency as function of distance

So the Doppler effect says that the frequency of sound changes due to relative motion of source and observer. My question is if there any expression that tells how the apparent frequency changes in ...
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Doppler shift in Acousto-Optic modulators

The interaction between a beam of light and an acoustic wave is commonly modelized as a photon-phonon scattering phenomenon. Applying the conservation of energy we have that  \hbar\nu_1=\hbar\nu_0\...
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Doppler effect and frame of reference

We know that in an inertial frame we can never tell if the frame is really at rest or moving with constant velocity but can’t we check if there is a change in frequency by a sound emitted by the frame ...
A space-craft, also of rest-mass $M_0$ and initially at rest, is propelled by reflecting a plane-parallel beam of photons, generated at a rate $αM_0$ from a stationary source mounted on the launch pad,...