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

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555 views

Can electrons change the frequency of light as they bounce off/around?

I know that light does not interact with other light, but can interfere it, at least its amplitude. With that said, lights frequency can be changed via bouncing off matter, where matter might absorb ...
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3answers
294 views

Why is 'the period' marked as letter T?

I'm not a native English speaker and I was wondering, why 'the period' got the letter $T$. I've asked myself the question when I was thinking about stuff related to the frequency. I.e.: $f$ - ...
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1answer
662 views

Relationship between classical electromagnetic wave frequency and quantum wave function + de broglie frequency

As it is. As I study through classical mechanics and quantum mechanics, I began to wonder whether there is a relationship between classical electromagnetic wave frequency and quantum wave function ...
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2answers
2k views

The energy of an electromagnetic wave

The intensity of an electromagnetic wave is only related to its amplitude $E^2$ and not its frequency. A photon has the same wavelength as the wave that's carrying it, and its energy is $h f$. So ...
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3answers
825 views

How does energy depend on frequency in an alternating current circuit?

In what relation is the energy input in an alternating current circuit to its frequency? I'd guess I have to compute something like $$E=\int P(\omega,t) dt=\int U(\omega,t) I(\omega,t) dt, $$ but ...
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5answers
209 views

Light refraction and causality

One way how to look at refraction by a dielectric medium like water or glass is that (phase) velocity of light decreases because it is the wavelength rather than the frequency of the light which ...
3
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1answer
880 views

Static flow of water in the presence of a loudspeaker

The title, I don't know whether it's correct or not, but I came across a video in youtube, http://www.youtube.com/watch?v=_PkgQQqpH2M. The author of video used the title and hence I used the same. ...
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2answers
315 views

When to use $f$ and when $\nu$ signifying frequency?

When to use $f$ and when $\nu$ signifying frequency? I guess that when you mean frequency of electromagnetic wave, you use $\nu$, and $f$ otherwise?
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2answers
2k views

Strategies against 50 Hz mains hum on detector signals?

I'm having problems with a strong 50 Hz mains hum on signals created by photodetectors. I assume that they are due to ground loops and I realize that the best option would be to remove those. What are ...
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3answers
43k 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?
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7answers
11k 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 ...
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1answer
837 views

Angular frequency. Wrong interpretation at Wikipedia?

This and this articles mention that the angular frequency is: number of oscillations per unit of time But this doesn't seem to be correct since the angular ...
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1answer
620 views

resonance frequency [closed]

A string has a mass per unit length of 9 10–3 kg/m. What must be the tension in the string if its second harmonic has the same frequency as the second resonance mode of a 2m long pipe open at one end? ...
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5answers
3k 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 ...
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1answer
145 views

Will a photon emitted from something moving quickly have a shorter wavelength?

If a photon is emitted from a light source moving at any speed, the photon will nonetheless always move at c (assuming it is emitted in a vacuum.) If the speed of a photon's emitter cannot influence ...
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6answers
6k views

Limit of human eye flicker perception?

I am designing a LED dimmer using software-controlled Pulse Width Modulation, and want to know the minimum PWM frequency that I must reach to make that LED dimming method indistinguishable from ...
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2answers
1k views

Can 2 beams of ultraviolet light intersect and be visible where they intersect?

Is it possible that if you have 2 ultraviolet lasers, that are invisible to the human eye, and if you aim their beams to intersect at some point, that the place of intersection will show a lower ...
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6answers
3k views

How to Make RF Waves Visible

I understand RF (Radio Frequency) Waves are electromagnetic waves and a mode of communication for wireless technologies, such as cordless phones, radar, ham radio, GPS, and television broadcasts. Most ...
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2answers
590 views

The definition of “frequency” in different contexts

I have been doing some research on all kinds of sound-related topics lately and have been a bit confused by the different uses of the term "frequency". Of course, the most general meaning of frequency ...
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1answer
984 views

Effects of high frequency lighting on human vision?

I have a couple of different LED flashlights. One of them has three different "modes" of brightness, and the way it controls it is via pulse width modulation (PWM). Here is a picture that illustrates ...
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1answer
255 views

How much power can be drawn from stray electromagnetism in the atmosphere?

I know this probably varies quite a bit from place to place on earth. But just some rough estimates: if I were to pull power via multiple antennae tuned to a variety of different frequencies, how much ...
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1answer
622 views

Changing magnetic flux graph?

In regards to a graph of the changing magnetic flux in a generator such as this one: a) The equation of the graph should be $\Phi = BA \cos \theta$. As $\theta=\omega t$ (angular velocity*time), ...
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2answers
194 views

Multiple channels of information in single electromagnetic wave?

I'm trying to understand how can multiple radio stations transmit information just by transmitting using different frequency. The way I understand it all those different frequency waves add up to a ...
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3answers
985 views

What is the specific meaning of “Fourier frequency” (as opposed to simply “frequency”)?

I've noticed that many journal articles (in optics) use the phrase "Fourier frequency" to describe, well, the frequency of something. Google scholar search for "Fourier frequency". Example: ...
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1answer
179 views

range of infrared light

I notice in the EMS chart that only half of the IR range will travel through the earth's atmosphere. So in the range of frequencies that penetrate the atmosphere what frequency travels farthest?
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1answer
264 views

Why is it that when driving in a car, and a lightning bolt strikes, my AM radio gets cut off for a while, but FM stays on?

I noticed this one day, a lightning/thunder occurred and my Fabulosa Spanish music died for a second. But not FM?
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2answers
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How can a Human voice or animal voice have unique frequency

Well this is pretty noobish question and I am not sure how to ask. When We talk we don't talk in an uniform frequency. Then how can one measure frequency of ones sound/voice ? I am asking this cause ...
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3answers
201 views

5MHz RF pulse frequency analysed in software

Is there software available that can analyse a 5MHz RF pulse to give a plot of frequency spectrum. The signal data is visible on a LCD screen or a print out could be obtained.
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4answers
727 views

How to calculate the quantum expectation of frequency of a particle?

I know how to calculate the expectation of < $\Psi$|A|$\Psi$ > where the operator A is the eigenfunction of energy, momentum or position, but I'm not sure how to perform this for a pure frequency. ...
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3answers
1k views

How could this person have discovered the resonant frequency from this string of magnets?

I stumbled onto this page http://mylifeisaverage.com/story/1364811/ and the post states that they were all making strings and shapes with these sets of 216 really small spherical earth ...
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3answers
906 views

Can we transport energy over infinite distances through vacuum using light?

I know that light (or electromagnetic radiation in general) attenuates in intensity as the square of the distance it travels. Why does it attenuate? Are the photons being scattered by the medium ...
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1answer
214 views

Radio waves and frequency of photon

Is 89MHZ station emitting photons of 89MHZ frequency? (I mean $\nu$ in $E=h\nu$).
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2answers
17k 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 ...