The doppler-effect tag has no wiki summary.
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Hearing a sound backwards because of Doppler effect
Consider a supersonic plane (mach 2) aproaching a stationary sound source (e.g a fog horn on a boat).
If I understand it correctly, the passengers in the plane can hear the sound twice. First at a 3 ...
6
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2answers
177 views
Blue-shifting as opposed to violet-shifting
A recent XKCD comic implies that the sky is blue as opposed to violet due to human physiology, and that animals more sensitive to shorter wavelengths will perceive the Earth's sky as the shortest ...
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2answers
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In terms of the Doppler effect, what happens when the source is moving faster than the wave?
I'm just trying to understand this problem from a qualitative perspective. The Doppler effect is commonly explained in terms of how a siren sounds higher in pitch as it is approaching a particular ...
5
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1answer
215 views
Meaning of negative frequency of sound wave
Suppose that Alice and Bob are both holding speakers emitting sound at a frequency $f$. Alice is stationary while Bob is moving towards Alice at twice the speed of sound.
In the case of Alice, if I ...
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2answers
513 views
How do you measure distance to stars within the galaxy?
I know that for close by stars (<50 LY) we can use the parallax effect. And for distant galaxies we use red-shift (& hubble's constant). So how do we measure how far is a star lets say 50,000 ...
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5answers
503 views
Sound frequency of dropping bomb
Everyone has seen cartoons of bombs being dropped, accompanied by a whistling sound as they drop. This sound gets lower in frequency as the bomb nears the ground.
I've been lucky enough to not be ...
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2answers
81 views
Is there a way to create a flickering frequency to be dependent on speed of the person looking at it?
Is there a way to make a screen or a road sign flash at different rates, depending on the velocity of the observer looking at it?
I would like to achieve a state where two observers going at ...
3
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5answers
164 views
Will a warm body naturally slowdown?
Suppose a warm body moving in an empty space with high speed.
The body emits radiation based on its temperature. The protons emitted forwards of the body will have higher energy due to Doppler shift ...
3
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1answer
121 views
Wave equation for sound waves and moving source
Is there a way to take a moving source already into account when one derives the wave equation for sound waves and derive from that using only math the Doppler effect for moving sources?
3
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5answers
632 views
Doppler effect of sound waves
I am looking for interesting ways to introduce the Doppler effect to students. I want some situations in nature or every day life, where a student is possibly surprised and may ask "how could it be"?
...
3
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1answer
261 views
Doppler cooling limit vs recoil limit
I was discussing laser cooling in class today and I understood that the main principle of the process is to tune a laser to a frequency lower than the absorbtion frequency of the atom and so only the ...
3
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4answers
278 views
How does the Hubble Redshift work?
I am a little confused about the workings of the Hubble Redshift. I do understand the classical Doppler-effect, however in special relativity the velocity of light c is a natural velocity limit. So ...
3
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1answer
78 views
How would I perceive a purple ball when traveling at relativistic speeds
I have a 'thought experiment' which I'd like to ask about.
I was thinking what speed I would have to drive towards a crossing to see a red light as a green light - pretty easy, using the doppler ...
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2answers
335 views
quantum explanation of doppler effect
How would quantum mechanics explain doppler effect?
And just for curiosity, is there any effect similar to doppler effect occuring at quantum level?
2
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3answers
251 views
How many boats does it take to find an acoustic buoy by Doppler shift?
Inspired by this question on the Doppler shift, suppose there is buoy somewhere on the surface of the ocean emitting a pure frequency.
You get to place some boats wherever you want on the surface of ...
2
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4answers
532 views
Why did we need relativity to derive $E=mc^2$?
Okay, so the way I understand one of the "derivations" of $E=mc^2$ is roughly as follows:
We observe a light bulb floating in space. It appears motionless. It gives off a brief flash of light. We ...
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4answers
854 views
Doppler effect from an accelerating frame of reference
The standard equation for the doppler effect from a frame of reference with constant velocity is
$f_0$ initial frequency;
$v$ is the velocity of waves in the medium;
$v_r$ is the velocity of the ...
2
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1answer
120 views
Is the classical Doopler Effect, for light shift, $1-v/c$, exact? What is it an approximation of?
Is the classical doopler effect for light shift equal to $1-v/c$ exact or an approximation of a classical formula? I know that it is an approximation of the relativistic formula, but what was the ...
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2answers
125 views
Relativistic Doppler effect derivation
This is about a step in a derivation of the expression for the relativistic Doppler effect.
Consider a source receding from an observer at a velocity $v$ along the line joining the two. Light is ...
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1answer
151 views
How does Doppler effect differ between EM -waves in Electrodynamics and Sound -waves?
I have an electrodynamics -course that contains doupler -effect but unfortunately with little explanations. Is it the same thing as the classical doppler effect for example with sound, more here, or ...
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1answer
57 views
Pound-Rebka-Snider experiment in the inertial frame
In Schutz's book (page 120), Schutz first derives the gravitational redshift in the PRS experiment in a previous paragraph.
$\frac{\nu^{\prime}}{\nu}=\frac{m}{m+mgh+O(v^4)}=1-gh+O(v^4)$.
Here ...
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1answer
223 views
Relativistic Doppler effect
If i have 2 coordinate systems (CS) which are travelling one towards another. CS $xy$ with an observer in its origin and CS $x'y'$ with a source in its origin. Correct me if I am wrong, but i think ...
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1answer
112 views
Why does heterodyne laser Doppler vibrometry require a modulating frequency shift?
On the wikipedia article (and other texts such as Optical Inspections of Microsystems) for laser Doppler vibrometry, it states that a modulating frequency must be added such that the detector can ...
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0answers
230 views
How to find orbital radius of star in a binary system using redshift and orbital period data? [duplicate]
Possible Duplicate:
About binary stars and calculating velocity, period and radius of their orbit
I am given the non-redshifted wavelength of the EM radiation from one of the stars, the ...
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3answers
251 views
Doppler effect “apparent frequency”
In discussing Doppler effect, we use the word "apparent frequency". Does it mean that the frequency of the sound is still that of the source and it is some physiological phenomenon in the listener's ...
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2answers
74 views
Independence of frequency in sound waves?
Why does the frequency of sound wave depend only on the source? Why is the frequency and not any other "quality" independent of everything but the source?
And that said, why is velocity and ...
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1answer
45 views
Red/Blue Shift in EM Waves
A Doppler weather radar operates at a frequency of 3.40 GHz. The wave
from this radar system reflects from an approaching weather system
moving with a speed of 39.0 m/s. What is the difference ...
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1answer
78 views
Senior High School work on Doppler measurements
Sorry this question is really vague- as a result I'm very confused. Perhaps you can help me make sense of it.
"Radar measurements: Construct a space-time diagram of the radar tracking of an asteroid ...
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2answers
61 views
Special Theory of relativity on electromagnetic waves
Since time slows down and length contracts, when we travel almost at speed of light, if the speed of light (or EM waves) remains same and the wavelength of light remains same, do we measure the ...
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0answers
184 views
Is there an easy derivation of relativistic velocities addition and relativistic doppler shift?
Is there an easy derivation of relativistic velocities addition and relativistic doppler shift?
I'm looking for some easy derivation of the above. Like this ...
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0answers
48 views
How could I get to $E=mc^2$? [duplicate]
Possible Duplicate:
Did Einstein prove $E=mc^2$ correctly?
What was Albert Einstein’s proof for $E=mc^2$?
I wanted to know, How did Einstein come up with $E=mc^2$. I read it´s related to ...
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1answer
155 views
Are all effects that change color perception examples of redshift/blueshift?
As defined by Wikipedia:
In physics (especially astrophysics), redshift happens when light seen coming from an object that is moving away is proportionally increased in wavelength, or shifted to ...
