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Questions tagged [frequency]

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

Frequency is the rate of repetitive aspect in the amplitude over a given dimension. Most often questions with this tag will be related to the units of one over seconds. But it is important to note that spatial frequencies and even frequencies in the dimensions of force may also require this tag. A frequency will have units of one over the dimension in which the frequency is measured.

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Why are the harmonics of a piano tone not multiples of the base frequency?

I was trying to figure out which piano keys were being played in an audio recording using spectral analysis, and I noticed that the harmonics are not integer multiple of the base note. What is the reason for this? Take a look at the spectrogram of…
Szabolcs
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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: Walked away from the car until I was out of…
Yababaa
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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 on the detritus around it. Sept. 9, 2003: Astronomers…
Aarthi
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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 you need to keep constant: the wavelength or the…
user541686
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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 of magnitude was selected. I.e., why 50 Hz and…
SuperCiocia
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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 believe that low sounds carry longer…
Max
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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?
Self-Made Man
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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 different frequencies. This is known as dispersion. My…
Brandon Enright
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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 works and gives meaningful results that we can…
Schizomorph
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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 frequency of $2x$. So here's my childhood toy…
Moctava Farzán
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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 the same on the opposite side?) My thoughts: If…
Hritik Narayan
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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 the far away galaxies is red shifted and I could…
OCTAV
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Why aren't we bumping into objects outside of the visible range?

Apologies if this is too simple of a question for this site. My physics education stopped at the undergrad level. My 12 year old nephew asked me a question and I couldn't give him an answer. He asked, upon learning the human eye could only see…
gary
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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 something as soft as a towel creates sound when you…
user929304
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How do headphones and earphones produce good bass if tiny speakers can't produce low frequency sounds very well?

It's a well known fact that small/tiny speakers cannot produce low frequency sounds very well. Conversely, large speakers cannot produce high frequency sounds very well. Hence the need for tweeters and woofers in your speaker systems. But, how do…
navigator
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