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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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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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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41 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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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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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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What does the ratio (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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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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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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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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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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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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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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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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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?
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Why do lines in atomic spectra have thickness? (Bohr's Model)

Consider the atomic spectrum (absorption) of hydrogen. The Bohr's model postulates that there are only certain fixed orbits allowed in the atom. An atom will only be excited to a higher orbit, if ...
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CMB anisotropy, temperature and doppler effect

How would you derive the following equation: $$ T' = T_{CMB} \left( \frac{\sqrt{1-v^2}}{1+v\cos{\theta}} \right) $$ which describes how the temperature of the CMB varies due to the speed $v$ of the ...
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Relativistic doppler effect in three dimensions

Consider a sphere that travels through space with a velocity $v$. I wish to investigate the relative intensities of the CMB on all points on the sphere. For the microwaves approaching from the direct ...
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Does Doppler Effect violate Galilean relativity?

Apparent frequency when the source is moving away from the observer the relation between the frequencies is: $$f' = \frac{v}{v+ v_{s} } f$$ Apparent frequency when the observer is moving away from ...
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Cooling atoms using emitted photons from a laser cooled atom

In Doppler cooling procedure, is it theoretically possible to use the emitted photons from the target atom (cloud) to cool more atoms? The idea is to cool the atoms rapidly by using energy emitted by ...
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Doppler velocimetry accuracy

The formula is : $$v = \frac{c}{2\nu_e cos(\theta)}\Delta\nu$$ and the measured velocity is supposed to be more accurate when $\Delta\nu = \nu_d-\nu_e$ decreases. How can we see that from the ...
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Does “apparent frequency” mean the Doppler effect is not an actual physical effect?

When discussing the Doppler effect, we use the word "apparent frequency". Does that mean that the frequency of sound is still that of the source and that it is some physiological phenomenon in the ...
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Red/blue shifting out of visible spectra

How fast would a white light (emitting only visible spectra) need to travel in order to red or blue shift so far its no longer visible? Are some stars completely invisible due to this effect?
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What is meant by a “sodium line”?

What speed should a galaxy move with respect to us so that the sodium line at $589.0\ \mathrm{nm}$ is observed at $589.6\ \mathrm{nm}$? In the above question what's meant by a sodium line? The ...
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Doppler shift and special relativity

I have been listening to an audio course on Special Relativity. In the course the teacher repeatedly says that the "laws of physics are equally valid for all uniformly moving frames of reference". ...
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Why would a sweeping LIDAR or RADAR beam not produce an artificial Doppler shift?

Assuming a bi-static Radar or LIDAR with a stationary transmitter and a stationary target and a stationary receiver, with a sweeping RADAR/LIDAR beam reflecting off a stationary target: Why would the ...
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Why doesn't the speed of the wind have an effect on the apparent frequency?

A boy is standing in front of stationary train. The train blows a horn of $400Hz$ frequency . If the wind is blowing from train to boy at speed at $30m/s$, the apparent frequency of sound heard by the ...
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Beat Frequency for Police Radar with Special Relativity

"A radar speed trap operates on a frequency $v_o = 109 Hz$. What is the beat frequency between the transmitted signal and one received after reflection from a car moving at v = 30 m/s toward the ...
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Apparent frequency and wavelength in the Doppler effect

For a transverse wave(or for pressure waves required to produce longitudinal waves), the motion perpendicular to the direction of propagation of the wave is governed by an equation like $y = ...
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Would cosmological redshift be present in the following situation?

I'm trying to understand if cosmological redshift is just a secondary form of doppler redshift, or something else entirely. Suppose the two galaxies in the picture are receding from each other, but ...
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Tired light red shift hypothesis

Have there been any recent attempts to falsify the tired light hypothesis alternative to the Doppler shift explanation for the red shift, or is it simply ignored like the pilot wave quantum mechanical ...
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The Doppler shift and the apparent speed of galactic rotation with distance

A Doppler redshift would also give the illusion that galaxies were rotating more slowly then they are with the degree of illusory slowing in proportion to the degree of redshift. Do more distant ...
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Proof of expression to combine different redshifts

I am trying to arrive to the following expression: $1+z = (1+z_C)(1+z_G)(1+z_D)$ so the total redshift is the product of the cosmological redshift, the gravitational redshift and the Doppler ...
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Could I see the cosmic microwave background if it were Doppler shifted enough?

If I traveled fast enough, my current understanding is that visible light would be blueshifted to the blue/UV range, but also that microwaves and longer wavelength waves would be blueshifted into the ...
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How does doppler shift makes any sense?

Consider this. The reason we see red at dusk is because the sun is away from us, and thus the wave length is longer, which corresponds to the color red. But think of a transmission line that is over ...
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Is there any difference in radiation pressure for two observers in different gravitational potential?

Suppose that a light beam is shone upwards from surface of a planet. So, due to gravitational redshift, the frequency of the light perceived by observer far from the surface will be lower than that ...
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Will the frequency of the reflected wave of a moving source be shifted by Doppler effect?

I want to know if there is a moving source that emits wave to a reflecting object like a wall for example, then, will the frequency of the reflected wave be shifted because of the Doppler effect. As ...
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Doppler Effect: What is formula for Rate of Change of Period observed by accelerating receiver?

(I have looked at other questions relating to Doppler Effect with acceleration but none seem to provide the formula in question.) Edit: I wish to avoid using the Einsteinian relativity model. So ...
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How did the Huygens probe use EM waves to measure wind speeds on Titan?

In the Wikipedia's article on Huygens spacecraft, it was mentioned that one of the experiments was to measure the wind speeds on Titan by Doppler wind experiment. To quote the exact lines, it was ...
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Center of mass of two $\gamma$ rays moving in opposite directions

Suppose there are two $\gamma$ rays with frequencies $\nu_1$ and $\nu_2$ moving in opposite directions according to a reference frame $S$. I want to find the velocity of the center of mass of this ...
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Frequency of flute note heard using Doppler effect when both the source and observer are moving

Let us consider this scenario. A bicycle rider and a flute player are moving in the same direction at speeds 36 km/h and 18 km/h. The flute is producing a note of frequency 600 Hz. We need to find ...