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

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Why 50 Hz frequency is used in india? [on hold]

I want to know why the specific frequencies used in certain countries, for example 50Hz, 60 Hz. Also what is the effect of frequency on transmission?
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1answer
32 views

AM vs FM radio under bridges

I know what the difference between AM (Amplitude Modulation) and FM (Frequency Modulation) radios is. However, I noticed that when I drive under a bridge while listening to a station on AM, it just ...
3
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1answer
29 views

Frequency-averaged (gray) radiative transfer

The equation for radiative transfer is $$ \omega \cdot \nabla I = \kappa(B - I) $$ where $I$ is the intensity of radiation, $\omega$ is the ray direction, $\kappa$ the absorption coefficient, $B$ the ...
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21 views

light color and refraction

I'm a bit confused on the topic of refraction, some starting premises: 1) When light refracts from exiting a medium with a low n and entering a medium with high n the light bends. 2) The index of ...
3
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4answers
133 views

What does it mean by complex frequencies? (Quasinormal Modes)

Something I've taken for granted and not yet thought about physically, is how the frequency of quasinormal modes related to a black hole are $\textit{complex}$. I know that it's something to do with ...
3
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1answer
74 views

Image Reconstruction:Phase vs. Magnitude

Figure 1.(c) shows the Test image reconstructed from MAGNITUDE spectrum only. We can say that the intensity values of LOW frequency pixels are comparatively more than HIGH frequency pixels. $$ ...
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1answer
13 views

How to compute $L_{\rm eq}$ from temporal pressure data

I have pressure vs time data. how can I compute sound equivalence Level $L_{\rm eq}$ in decibels? can this be done from a frequency spectrum assuming that it is constant?
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1answer
46 views

Understanding frequency of a signal

I'm trying to understand how can one transmit different signals on a same copper wire using different frequencies. How does the electrons actually interact with the frequency? And how does the ...
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1answer
19 views

is it possible to change the energy of a waveform like radio wave & turn it into microwave?

In the electromagnetic spectrum, the differences between all waveforms are the "frequency" & energy of the waveform. We are able to modify both of these parameters. So, is it possible to change ...
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23 views

Can temperature affect or change the wavelength or frequency of EMR?

If we were to emit Electro Magnetic Radiation(X-rays for example) to a very hot body such as the sun would we still get X-rays if we had a capturing device at the other end or would the high ...
8
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3answers
326 views

Is there physics behind the layout of a piano keyboard?

We have 12 different 'notes' per octave on a musical keyboard. They are set up so that every 'note' (A, B,C etc) is a second harmonic of the same 'note' in the next higher octave. With this ratio in ...
4
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2answers
1k views

What is the symbol Å?

I saw this symbol like: $$\lambda=3000\overset{\circ}{\text{A}}$$ and I don't know what this means. Is it a frequency? (since $\lambda$ is usually used for frequency)
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5answers
170 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 ...
2
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0answers
37 views

De-excitation and vibrational frequency

By utilising energetic beams of particles it is possible to set atomic nuclei into vibration. For a certain nucleus the subsequent de-excitation results in the emission of photons of energy $1$ $MeV$. ...
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1answer
41 views

If I had a 1cm iron sphere that I could vibrate at an rate, how fast would it have to be vibrating before it could not perceived by sense of touch?

Is there a vibratory rate at which my hand would just pass right through the object and it could not be perceived by touch anymore?
2
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0answers
29 views

How do the single photon energy and em-signal energy correlate? [duplicate]

If the photon (as a quantum of the electromagnetic field) has no defined(?) amplitude, how does (or where from?) the electromagnetic wave's amplitude appear? The formulation of the question is not ...
1
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1answer
28 views

Resonating frequencies of atoms

I have a mathematics and computer science background with very little physics. I have read that the resonating frequency of an atom of some element is always exactly the same as the resonating ...
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2answers
66 views

What does a constant signal sound like?

Say I was sampling a sound incorrectly and it produced a constant signal as below: What would this signal sound like? In Matlab, it plays nothing. Is this correct?
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2answers
59 views

Is there just one fundamental frequency?

I read simple definitions of the terms frequency, and fundamental frequency, which defined them thus, Frequency: the number of occurrences of a periodic wave during a second Fundamental Frequency: ...
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2answers
240 views

How does the frequency of a particle manifest itself?

In terms of wave-particle duality for, let's say a photon; how would the frequency practically manifest/demonstrate itself? Like, i understand that the frequency is related to the energy a particle ...
0
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1answer
205 views

Difference between angular frequency and angular velocity?

What is the difference between angular frequency and angular velocity? I think one is used for SHM and the other for circular motion? Also can both be used for centreptal accelartion? I think angular ...
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3answers
82 views

Does frequency f = $\frac1T$ if there is non-periodic signal

Through what I learned from school, frequency $f=\frac1T$ while $T$ is the period. However, things get harder in college where there are non-periodic signal. That means they have no period or their ...
4
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2answers
291 views

Frequency of touch, taste, and scent [closed]

So I was thinking about sound - and how anything below 20Hz is basically inaudible to humans (because it is too low of a frequency to be recognized), as well as anything above around 20KHz (because it ...
0
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1answer
49 views

Does sound absorption depends upon the amplitude of sound wave?

I can understand the mechanism of frequency dependant sound absorption by most materials but does the sound attenuation also depends upon the AMPLITUDE(sound pressure or rather loudness/sound ...
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2answers
107 views

Does the Sun produce audible sound?

Theoretically if I were able to build some sort of device that let me sit 1 foot away from the surface of the Sun (or any star for that matter) without being vaporized, would a star produce any sort ...
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1answer
158 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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2answers
26 views

Rotational Velocity and Rotational Frequency

What is the difference between rotational velocity & rotational frequency? Their units seem to be the same, and I've read that one is a 'scalar' and the other is a 'vector,' but how do they ...
0
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1answer
28 views

Horsepower at certain RPM point without knowing torque?

I want to know the horsepower produced by an engine at certain RPM by knowing another certain RPM point? Let's suppose that an engine produces 200 hp at 4000 RPM, how many horsepower is produced by ...
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1answer
179 views

Will a sound composed of the frequencies 450Hz, 650Hz 850Hz have a clearly defined musical pitch? Why?

According to my lecturer, the perceived pitch of a sound composed of the following harmonics: 750Hz, 1000Hz, 1250Hz is equal to the fundamental frequency which is the highest common factor of the ...
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6answers
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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 ...
2
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1answer
90 views

Red color has largest wavelenght and violet minimum (in the range of visible light). then why does violet light appears reddish? RED + BLUE = VIOLET [duplicate]

My question is simple. Green light is more similar to red light than violet, then why is violet reddish and green not? in the language of frequencies and wavelengths, red and violet should contrast ...
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1answer
137 views

Calculating the energy of an electron given the wavelength

Okay, so I know that the wavelength of an electron is 5e-7m and I am asked to calculate its minimum velocity and hence minimum energy. Calculating the minimum ...
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2answers
94 views

Can someone please explain the “infrared catastrophe”?

In my readings I've run into this idea of an "infrared catastrophe" associated with 1/f noise. As far as I can tell it is because when you graph the periodogram of the 1/f signal you see the PSD goes ...
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84 views

How is extremely low frequency (ELF) radiation collected by a submarine antenna?

The U.S. Navy Project ELF managed to generate extremely low frequency (ELF) radiation at down to $\approx 76$ Hz (implying a wavelength of $\approx 3,945$ km!). I was curious, what kind of receiving ...
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32 views

Math formula for crystal glass resonance [duplicate]

For a music therapy experiment, I have to use several crystal glasses with water and different cylindrical shapes, and make them vibrate and produce different sounds. Is there a math formula that ...
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0answers
182 views

How would you go about finding the natural frequencies (resonance frequency) [closed]

How would you go about finding the natural frequencies of solid materials like wood (e.g., teak, pine), stone (e.g., marble, granite) liquid, etc?
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1answer
75 views

Is Sound Considered a Subtopic of Physics? What are the SI Units of Sound?

Does physics cover sound? If so, why does sound not have units in the SI system, or how would we measure sounds and frequency? I guess it's debatable, but why isn't it standard practice in physics?
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32 views

help me.. please [duplicate]

I'm a total novice to physics so please forgive me but I'm looking for a starting point on sound, frequencies and everything to do with electricity. Preferably books because my internet usage is ...
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Why does a remote car key work when held to your head/body?

I was trying to unlock my car, 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: Walked away from ...
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1answer
84 views

Two masses attached by a spring [closed]

Suppose there is a system of two masses $M_1$ and $M_2$ connected by a spring with constant $K$ on a frictionless surface. What is the frequency of this system's oscillation? So I have fixed a ...
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4answers
311 views

Can frequency be equal to 0?

Is correct to speak about frequency equal to 0 ? $$f= \frac{1}{t} $$ If $t\rightarrow\infty$ can I consider that the frequency is equal to 0 ?
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60 views

Would it be possible to distinguish rap and singing from just seeing the soundwaves?

For any person even remotely familiar with music it is obvious that rap and singing are easily distinguishable (save for some interesting mix styles). This means that there must be a clear difference, ...
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2answers
51 views

Frequency of Light Near a Massive Object

We know that near a massive object, light's wavelength and frequency changes, but its speed remains same. I'd like to know how it is possible for frequency to change, unless we change the light ...
2
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2answers
72 views

How does one measure the frequency of a laser?

I am taking a short introduction course on lasers. I never knew that the frequency of a laser is so high for a given wavelength (e.g. 780nm). I am wondering how people can measure the frequency of the ...
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2answers
647 views

Why does noise affect FM radio less than AM?

Frequency modulated waves are less susceptible to noise compared to amplitude modulated signal. This is because the information in an FM signal is transmitted through varying the frequency, and not ...
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230 views

Why are two independent sources incoherent?

Coherent sources are produced from a single parent source. But, why are two independent sources always incoherent? Two sources can produce light of the same frequency. Then, I guess the problem is ...
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114 views

Frequencies of Matter [closed]

Is it theoretically possible for physical solid matter to vibrate at a high enough frequency to become imperceptible to vision and move through other solid matter?
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3answers
180 views

How to calculate Standing Waves in Electrical Cables?

I have a 20 metre Coaxial Cable. I send digital signals down the cable ranging from 5 KHz to 50 KHz. I have noticed a pattern in the noise ratio, an oscillating wave. I predict this is to do with ...
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35 views

Resonance force with multiple emitters

Will I get a stronger resonance if I put multiple frequency generators around the same object? example image