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Questions tagged [wavelength]

The wavelength of a sinusoidal wave is the spatial period of the wave—the distance over which the wave's shape repeats, and the inverse of the spatial frequency or wavenumber. Determined by considering the distance between consecutive corresponding points of the same phase, such as crests. Use for wavenumber, wavelength, frequency.

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25 views

Efficient generation of infrasound

It seems that the most common sources of infrasound are earthquake, tsunami, volcano eruption, etc, which are all large scale behaviors. Why is it difficult for a human to generate infrasound? Is ...
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Property of light in different media?

Shouldn't keeping a colored frame in front a flash light ( white light ) change its wavelength or frequency?But I have also learned that light doesn't change its frequency when going from one medium ...
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Looking for something to reflect ultraviolet light at extremely low wavelengths [closed]

I am looking for some sort of mirror that will reflect ultraviolet light at extremely small wavelengths (200-250 nm). The main purpose of it is to amplify the ultraviolet light and cause it to spread. ...
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A question on the properties of wave equations

When you change $$y(x,t)=A\sin(kx-ωt+φ) $$ into $$y(x,t)=A\sin(2kx-2ωt+φ), $$ does it double the wavelength because $k$ changes into $2k$ and double the frequency since ω is doubled? If this is ...
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How do we know electron have wavelength?

I know many people thought that light is a wave in the past before Einstein came along but what about electron, the scattering experiment could only hint at their existence so how do they know that ...
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119 views

Does glass convert light wavelength?

I heard that when sunlight enters house through windows, it gets converted into longer wavelengths and gets trapped inside. So does the glass have anything to do with this or is this about heated ...
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3answers
71 views

Wavelength and relativity

From de Broglie equation λ=h/p. But p=mv and velocity is a relativistic quantity so also wavelength is relative ? In other words does wavelength depends on the reference frame ?
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129 views

Why we do not use $v=f \lambda$ for the waves associated with particles?

As the waves travel with velocity $$v= f \lambda,$$ where $v$ is velocity, $f$ is frequency and $\lambda$ is wavelength. Here we can see that velocity of wave is directly proportional to wavelength. ...
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135 views

How the intensity of light is related to the light wavelength?

Light can be seen as a wave or a particle. Light as a wave is well described by Maxwell's theory. Light energy relates to its wavelength and momentum too. However, if we treat light as a particle what ...
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Paragraph from a Stephen Hawking's Book (Uncertainty Principle)

This is from a Stephen Hawking's Book (Uncertainty Principle). I would like to know how does the Uncertainty Principle impose a limit on the size. What does he mean? From Hawking's book: It turns ...
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What is the difference between Wien's Displacement Law for peak frequency vs peak wavelength?

While doing research for a high school report I came across the fact that WDL actually has two forms, one for peak frequency and one for peak wavelength, and that these two forms are not the same and ...
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How Negative Color Value is accepted in Tristimulus Values for Mixing Colors?

I read a chapter about Trichromatic Theory of Color Mixture (Yao Wang, et all. 2001), about how we can produce most colors by mixing 3 primary colors. And the amount of three primary colors required ...
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Black body/Sun radiation - λmax

The Sun's effective temperature is 5778K. Using Wien's law we can calculate the wavelength λmax in which we observe the maximum amount of radiation received from the black body. After doing the ...
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478 views

How to derive derive De-Broglie's wavelength equation?

I was only yesterday learning about the De-Broglie equation $$\lambda = h/p, $$ I thought I understood it until I came across a question similar to this Now I always knew that photons don't have any ...
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1answer
45 views

Converting $\mathrm{ps/nm}$ to $\mathrm{ps}^2$

I have a dataset in the unit $\mathrm{ps/nm}$ for many different $\lambda$ which I want to convert to $\mathrm{ps}^2$. I guess I can assume that I only deal with Gaussian bandwidths such that $1\ \...
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Could electrons with a certain wavelength pass through a hole, or chamber, smaller than their wavelength? [duplicate]

I always thought, an electron could not pass through a hole, with a diameter, which is smaller than its wavelength. Just like microwaves could not pass through a metal mesh with small holes, but ...
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Is there such a material that only emits, or “sends out” the same color light that was “taken in” (absorbed)?

For example, glow-in-the-dark materials (photoluminescent) only emit a green hue regardless of the color of the light shone on the material. Is there such a material that emits the color of the light ...
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2answers
169 views

What is the physical interpretation of dividing $2\pi$ by a variable?

Looking at the angular wavenumber eqn: $$k = \frac{2\pi}{\lambda} = \frac{2\pi\nu}{v_p} = \frac{\omega}{v_p}$$ I'm curious what it means to divide $2\pi$ by the wavelength and why $2\pi$ was chosen....
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Percentage increase in wavelength leads to percentage decrease in energy. (Compton effect)

In this question: What percentage increase in wavelength leads to a 75% loss of photon energy in a photon-free electron collision? My understanding of this question is that $0.25\times E_i = E_f$, ...
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1answer
45 views

In order to observe a structure of length order of 1 femtometer, how large kinetic energy must the electron have?

According to the de Broglie relation, $\lambda=h/p$ where $h$ is the (not reduced) Planck Constant and $p$ is the magnitude of the relativistic 3-momentum. So, it should be that $\lambda$ should be ...
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1answer
151 views

De-Broglie wavelength from two different reference frames

If we were to measure the De-Broglie wavelength of a particle of mass $m$ and velocity $v$, in a given reference frame, it would be given as $$\lambda = h/p$$ (where $h$ is Planck's constant & $p$ ...
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Dispersion and wavelength

Why does dispersion increase with wavelength? If I understand correctly, refractive index is decreasing with wavelength. As a result, greater wavelengths are traveling faster. How does this cause the ...
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3answers
83 views

Does reflection preserve wavelength?

If a photon at a certain wavelength gets reflected on a surface, does the reflected photon have exactly the same wavelength? If not, what is the distribution of its wavelength? I know about up- and ...
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1k views

The relation between speed and wavelength

I was taught categorically that the velocity of a wave depends only on the medium in which it travels. Now I just stumbled upon a sentence + formula that declares that "the velocity of sinus-waves ...
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1answer
62 views

Photon frequency when transitioning from one medium to another

$E=h\nu$ where $\nu$ is frequency and $h$ is Planck's constant. The frequency, wavelength and speed are related as $c=\lambda\nu$. When transitioning from one medium to another the speed decreases by ...
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Can the em wave pass through matter obstacles and how?

I know about Faraday's cage, and another screens, but I do not understand the physics of this processes. Well, I know that the atoms are almost empty, so there are a lot of free space to em waves to ...
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How to convert cm$^{-1}$ to eV?

I know that $1 \:\mathrm{cm}^{-1} = 8065.54429 \:\mathrm{eV}$. I know that wave-number has unit $\:\mathrm{cm}^{-1}$ and that $E=hc\times \mathrm{wavenumber}$. But how do I arrive to the number $...
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204 views

What is the largest wavelength that can excite an atom?

What is the largest wavelength that can excite an atom? Or is there even a largest wavelength?
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Contradiction on the behavior of refractive index

The refractive index is given by: $$ n = \sqrt{\mu_r \epsilon_r} $$ This equation is symmetric about wavelength and is same for all wavelength of light i.e. since $\mu_r$ and $\epsilon_r$ are ...
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1answer
165 views

Can elementary particles be confined to a smaller region then their Compton wavelength?

I have read this question: Elementary particle (electron) and non-elementary (proton) spagettification and the comments where it says: But no real elementary particle can be confined in a region ...
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2answers
91 views

Does Wave-Particle duality exist at high speed?

I know that relativistic DeBroglie wavelength is given by $λ = h/γmv$. And $γ ≥ 1$, so at higher speed $λ$ will get shorter and shorter, does this mean it will start behaving like a particle and wave ...
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from a spectrometer, how to determine unknown substance in water?

I created a spectrometer that produces nice clean wavelengths, I calibrated it using a fluorescent bulb. from that I can create a graph from the data. after which, I use the known position to of ...
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1answer
379 views

Radio waves collision versus waves in a pond collision

Please see the attached picture: We are trying to show an image to visualize radio wave collision and interference with regards to Maritime AIS Technology. What do colliding radio waves have in ...
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2answers
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Is there a cap to EM wavelengths

I was just wondering, if there is a cap to the min and max of EM waves. like whats the smallest possible wavelength? the width of an electron? smaller? What kind of wave would that be? And what ...
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136 views

Effect on angular width of central bright fringe

In a single slit experiment when the light of a smaller wavelength is used what happens to the angular width of central bright fringe?
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222 views

Can ultrasonic waves become audible after “hitting” some object?

I recently found this article published in an Asian magazine, which claims the possibility of turning ultrasonic waves into audible sounds after "hitting" an object. A Japanese enterprise specialized ...
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1answer
152 views

Wein's Displacement Law for Light Bulbs?

I know Wein's Law $\lambda_{max}=\frac{b}{T}$ works for ideal black bodies. I have some clear glass incandescent light bulbs which have Tungsten as a filament. Would Wein's Law of displacement be a ...
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1answer
152 views

Why does a photon have to be one wavelength? [closed]

I've found nothing on this topic. Everyone says a photon is one wavelength of whatever beam of energy it belongs to, but no one says why this needs to be the case. If anyone has an answer, I'd be glad ...
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1answer
60 views

Why the purple and red light entering the prism is broken at different angles? [duplicate]

Lights entering the prism with different wavelengths at the same angle. why go to different directions? what happens step to step between the protons&electrons in glass and the photons? what is ...
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4answers
632 views

Why does this paper use 1/cm for units of frequency?

Reading this paper from 1963 $^*$, they use units of cm$^{-1}$ for frequency. Here is an excerpt: It doesn't seem like wave number, as they clearly call it frequency. What's going on here? $^*$ ...
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353 views

How to find out the wavelength for the blue led diode?

I need your help as I am stuck and I dont know where to start. I have got four blue leds diode that come with dark blue led lights that I really want to get the same led colours for my 3 fans, but I ...
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1answer
353 views

If the bound states to the infinite square well are stationary waves, why does the ground state consist of half a wavelength?

For a stationary wave, you need two counter-propagating travelling waves that 'reflect' off the boundaries of the well at either end then superimpose in the middle to produce a stationary wave. If ...
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2answers
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A pure sine wave vs. the infinite sum of its harmonics

Is a pure sine wave equivalent to the sum of its every harmonic (up to infinity and without the fundamental lets assume)? Moreover, if it is so, is this the reason why all the harmonics are present ...
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4answers
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Why does the wavelength of a particle go down with higher velocity?

In mechanical waves, the wavelength increases with a higher velocity. λ = v / f. And the wavelength in particles lower with a higher velocity. λ = h / mv.
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What is the fundamental wavelength of curved wind instruments?

For instruments such as a saxophone, is the fundamental wavelength still the whole length of the instrument even though it is curved?
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937 views

What is fundamental frequency, how does it make sense?

I’m currently going through harmonics, and I do not at all understand the fundamental frequency. I understand that it is the simplest vibration of a string, but I don't understand how can it have ...
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2answers
105 views

Do Electrons revolve with super-light speed? [closed]

Faster the particle, smaller wavelength. In the electron microscope, we use electrons because of its smaller wavelength? Does it mean electrons travel faster than light? Or simply measuring its ...
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What are upper reflectivity bounds of materials

I know that if i take metal-coated fiber i can send light signals to large distance, because signal would reflect inside fiber, lowering attenuation. Just like in optical fiber communication network. ...
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5answers
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Momentum of a photon equals Planck's constant over wavelength

A common identity in Quantum Mechanics is relation between the momentum of a photon and its wavelength: $$p = \frac{h}{\lambda}$$ The identity is discussed here, for example: https://en.wikipedia....
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Calculate distance between slits in diffraction grating?

I have a diffraction grating of $1,000$ lines $/$ $mm$, I am using a laser pointer of wavelength $\lambda$ $650$ to $670$ $nm$, (a red colour, which is observed). When I do the calculation using $1 / ...