Questions tagged [frequency]

Frequency is the rate of repetitive aspect in the amplitude over a given dimension.

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95
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7answers
20k views

How can a black hole produce sound?

I was reading this article from NASA -- it's NASA -- and literally found myself perplexed. The article describes the discovery that black holes emit a "note" that has physical ramifications ...
90
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9answers
186k views

Why does a remote car key work when held to your head/body?

I was trying to unlock my car with a keyfob, but I was out of range. A friend of mine said that I have to hold the transmitter next to my head. It worked, so I tried the following later that day: ...
82
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6answers
19k views

Why does public mains power use 50-60 Hz and 100-240 V?

Is there a physical reason behind the frequency and voltage in the mains electricity? I do not want to know why exactly a certain value was chosen; I am rather interested to know why that range/order ...
69
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5answers
134k views

Do low frequency sounds really carry longer distances?

It is a common belief that low frequencies travel longer distances. Indeed, the bass is really what you hear when the neighbor plays his HiFi loud (Woom Woom). Try asking people around, a lot of them ...
67
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11answers
100k views

What determines color -- wavelength or frequency?

What determines the color of light -- is it the wavelength of the light or the frequency? (i.e. If you put light through a medium other than air, in order to keep its color the same, which one would ...
62
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12answers
21k views

Are there pure sine waves in nature or are they a mathematical construct that helps us understand more complex phenomena?

I've studied a bit of frequency analysis with FFT and optimal phase binning and was taught that we can represent any composite waveform as the sum of its component frequencies. I understand the maths ...
61
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7answers
137k views

Why doesn't the frequency of light change during refraction?

When light passes from one medium to another its velocity and wavelength change. Why doesn't frequency change in this phenomenon?
58
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2answers
4k views

Why aren't the lengths of the bars on a toy glockenspiel proportional to the wavelengths?

As you might already know, frequency of musical notes is arranged in a such a way that if, for example, an A note has frequency of $x$, another A note which is placed one octave higher would produce ...
53
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4answers
11k views

Red shifted to what?

I searched and found a lot of questions and answers about red shift here but none with the answer to mine. (sorry if it is there somewhere and I did not find it.) Everyone is saying the light from ...
51
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4answers
26k views

Why do prisms work (why is refraction frequency dependent)?

It is well known that a prism can "split light" by separating different frequencies of light: Many sources state that the reason this happens is that the index of refraction is different for ...
47
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5answers
7k views

Are there any theoretical limits on the energy of a photon?

Is there any lower or upper limit on the energy of a photon? i.e. does the mathematical framework we currently use to study photons blow up when a photon surpasses a certain upper limit of energy? (or ...
45
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7answers
5k views

Why is it so easy to create audible sound?

Context Why is it so easy to create audible sounds in life with basically anything? Putting your cup of coffee on a table comes with a sound Turning a page of your book comes with a sound Even ...
39
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6answers
107k views

Why does medium not affect the frequency of sound?

I read in various places that frequency does not change with medium. Instead, wavelength changes in different mediums due to a change in speed. I understand why speed changes with medium, but I'm not ...
36
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7answers
11k views

Why can't you hear music well over a telephone line?

Why can't you hear music well well over a telephone line? I was asked this question in an interview for a university study placement and I unfortunately had no idea. I was given the hint that the ...
36
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3answers
5k views

Is it possible to estimate the speed of a passing vehicle using a musical ear and the doppler effect?

I've found a number of questions that concern the Doppler effect, but none that seem to address my question. I have a background in music. People with a musical ear can generally tell the ratio ...
34
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7answers
27k views

Is the light from the Sun the same as the light from a bulb?

I'm arguing with a friend of mine on whether the light emitted from the sun is of the same type of that emitted by a bulb. Her insistent ignorance is laughable, unless I'm wrong... She's talking ...
34
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3answers
178k views

Why does wavelength change as light enters a different medium?

When light waves enter a medium of higher refractive index than the previous, why is it that: Its wavelength decreases? The frequency of it has to stay the same?
34
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4answers
63k views

What is the highest possible frequency for an EM wave?

What is the highest possible frequency, shortest wavelength, for an electromagnetic wave in free space, and what limits it? Is the answer different for EM waves in other materials or circumstances? ...
31
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7answers
6k views

Would visible light still be in a separate classification if we saw "colors" in a different wavelength? [duplicate]

Basically im asking if there's anything special about visible light other than the fact that we use it to see colors. If we saw in another wavelength, would it still be possible to see colors like we ...
31
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3answers
2k views

Is there any truth to interpreting definition of a second as corresponding to oscillations?

As far as I understand the definition of a second, the Cs-133 atom has two hyperfine ground states (which I don't really understand what they are but it's not really important), with a specific energy ...
28
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6answers
3k views

Frequency difference when water splashes at different temperatures

When I pour hot water (near boiling) and cold water ($5 \unicode{x2103}$) from a height on a platform, there is a distinct difference in the sound that is generated. I feel that hot water splashing ...
28
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3answers
94k views

How does load affect frequency on the power grid?

This story about the use of battery/freewheel based Frequency Regulators confused me about how the 60hz frequency of the North American power grid was set--saying that it was kept at that frequency by ...
26
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3answers
7k views

If energy is quantized, does that mean that there is a largest-possible wavelength?

Given Planck's energy-frequency relation $E=hf$, since energy is quantized, presumably there exists some quantum of energy that is the smallest possible. Is there truly such a universally-minimum ...
26
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1answer
5k views

Are there naturally occurring lasers?

Are there natural processes we've discovered which lead to laser light of some distinct wavelength?
24
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5answers
41k views

How does power consumption vary with the processor frequency in a typical computer? [closed]

I am looking for an estimate on the relationship between the rate of increase of power usage as the frequency of the processor is increased. Any references to findings on this would be helpful.
24
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1answer
1k views

How can the rest-frame spectrum of redshifted light be determined? [duplicate]

The redshift effect must work on all frequencies, so blue would be shifted down to some lower frequency, and ultra violet would be shifted down also, into the visible area. How would you know what ...
23
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6answers
7k views

How can a red light photon be different from a blue light photon?

How can photons have different energies if they have the same rest mass (zero) and same speed (speed of light)?
23
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7answers
48k views

Why do bass tones travel through walls?

I was in the shower while my roommate was listening to music and got to thinking about the fact that I could only hear the bass and lower drums through the walls. Why is this? The two possibilities I ...
22
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6answers
112k views

Do all frequencies of light have the same speed?

Is there any speed difference between blue or red light? Is there ever a speed difference? Or do all types of light move at the same speed?
22
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7answers
5k views

The strange thing about the maximum in Planck's law

I read that it makes a difference whether you calculate $\frac{dE(\lambda) }{d \lambda}=0$ or $\frac{dE(\omega)}{d \omega}=0$ in the sense that the maximum energy density with respect to the ...
21
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4answers
5k views

Why do different letters sound different?

If one sings the letter "A" and "M" at the same volume and pitch, the two letters are still differentiable. If both pitch and volume are the same however, shouldn't the sound be the exact same?
21
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4answers
100k views

What makes some laser beams visible and other laser beams invisible?

What makes the beam of some lasers: visible? such as the ones used in clubs or such as the laser pointers sold at amazon which if pointed to the sky look like a solid visible beam of light crossing ...
21
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3answers
3k views

Non-resonant but efficient frequencies

I understand that if the frequency of a driving force coincides with the natural frequency of an oscillator (say a pendulum), the rate at which energy is transferred to the same is maximized. However, ...
20
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8answers
4k views

What does the "true" visible light spectrum look like? [closed]

When I google "visible light spectrum", I get essentially the same image. However, in each of them the "width" of any given color is different. What does the "true" ...
17
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5answers
13k views

Why do harmonics occur when you pluck a string?

When you energise a taut string, the following resonant modes of vibration occur: Plotting on the frequency domain, you can see their corresponding frequencies: But what is the underlying physical ...
16
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6answers
4k views

Why are red and blue light refracted differently if they travel at the same speed in the same medium?

When I look at Snell's law $\frac{\sin\theta_2}{\sin\theta_1} = \frac{v_2}{v_1} = \frac{n_1}{n_2}$ I don't see any reference to wavelength. If red and blue have the same speed in the same medium, why ...
16
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4answers
6k views

How are beats formed when frequencies combine?

I know amplitudes cancel (destructive) or combine (constructive) as per image below: (Source) But how do frequencies cancel out or combine? For some context: a question from my textbook A song is ...
16
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2answers
6k views

Why can't the human voice produce a Shepard tone?

Audio of a shepard tone on youtube. So what is a Shepard tone? A Shepard tone, named after Roger Shepard, is a sound consisting of a superposition of sine waves separated by octaves. When played ...
15
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3answers
7k views

How is a human voice unique? [closed]

Well, I am quite new to concepts of vocal sounds. From the physics point of view I believe a sound has two basic parameters i.e, frequency and amplitude. Considering the end sound wave produced by ...
15
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4answers
3k views

Is the frequency of light restricted?

What are the factors that limit the frequency of light? Can it have wavelengths ranging between zero and infinity?
15
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3answers
51k views

Does the human body have a resonant frequency? If so, how strong is it?

Inspired by this question on Music beta SE, I'm wondering if the human body has a strong resonant frequency. I guess the fact that it's largely a bag of jelly would add a lot of damping to the system, ...
15
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4answers
9k views

How can a Photon have a "frequency"?

I picture light ray as a composition of photons with an energy equal to the frequency of the light ray according to $E=hf$. Is this the good way to picture this? Although I can solve elementary ...
14
votes
10answers
4k views

Why does a capacitor act as a frequency filter?

What is it about a capacitor which allows it to filter frequencies? I understand the construction of a high-pass RC filter, and the mathematics behind it, but I'm struggling to find an explanation of ...
14
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4answers
2k views

What exactly was the "classical model" of black-body radiation, and what assumption about it made it wrong?

While studying black-body radiation, I saw that most of the textbooks and videos I watched mentioned that there was a contradiction between the classical model of black body radiation and ...
14
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7answers
1k views

What really determins the color of light? [duplicate]

I have been considering this problem: Colour is characterized by which of following character of light? a)Frequency b)Amplitude c)Wavelength d)Velocity Different websites claim ...
14
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6answers
24k views

How many colors exist?

How many "colors" do exist? Our perception: As far as I know, colors are just different frequencies of light. According to wikipedia, we can see wavelengths from about 380 nm und 740 nm. This means ...
13
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5answers
1k views

Why does light have multiple frequencies?

The wavelength of visible light ranges from 750 - 400 nm, and so do the corresponding frequencies. However, a photon only has one frequency, given by $E =h\nu$, at a given time, and it can’t be ...
12
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2answers
39k views

How do you measure wavelength/frequency of light

I'm sure this is a trivial question for someone who knows something about electromagnetic radiation, but: how do experimenters measure the wavelength/frequency of light? For example, how do we know ...
12
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6answers
13k views

Why does the frequency of a wave remain constant?

They say the frequency of a wave is its fundamental character, thus remain constant throughout its propagation regardless the medium through which it travels. Could anyone explain why frequency of ...
12
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2answers
4k views

Are small speakers inherently limited to higher frequencies?

I am hoping to build a subwoofer using multiple smaller speakers (165mm) instead of a single larger speaker (380mm). My theory is that the displaced air volume is what matters, not the individual ...

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