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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Wavenumber Equation Confusion

I have spent a frustratingly large amount of time grappling with this equation for wavenumber but I still don't understand. With the definition of wavenumber apparently being "the number of waves ...
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Why $c$ needs to be added in numerator and denominator while solving a de Broglie equation word problem?

15.3 Calculate the de Broglie wavleength of a 0.05 eV ("theremal") neutron. Making a nonrelativistic calculation, $$ \lambda=\frac{h}{p}=\frac{h}{\sqrt{2m_0K}}=\color{red}{\frac{hc}{\sqrt{2\left(...
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Excitation of hydrogen atom by visible light

Question statement: A beam of light having wavelengths distributed uniformly between 450nm and 550nm passes through a sample of hydrogen gas. Which wavelength will have the least intensity in the ...
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290 views

Effective wavelength

While measuring light from sky or anyother things we use photometer. If current flowing in photometer is proportional to intensity and frequency why there is something called effective wavelengths. ...
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112 views

Why does a 5GHz Wi-Fi signal experience less interference than its 2.4GHz counterpart?

I am thinking in this in terms of their respective wavelengths. The signal operating at a 2.4GHz frequency would have a significantly longer wavelength than the the other signal at a 5GHz frequency. ...
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Light wavelengths [closed]

So electron goes to lower energy state and emits photon with a specific wavelength. There are 7 electron cores, so 6!, or 720 different types of possible jumps. If all light is made from these 720 ...
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High speed data transfer over a fiber optic cable

Can someone please explain how can we transmit very high speed data (e.g. $10~\rm Gbps$) over fiber optics, knowing the fact that the wave that travels through the fiber is an optical wave (in the ...
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80 views

How to mathematically work out the color of the sky? [duplicate]

I was wondering if there is a way to mathematically work out the color of the sky, using the laws of geometric/wave optics.
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335 views

Derivation of Wien's displacement law

I know this might be a silly question, but is it necessary to know Planck's Law in order to show that $\lambda_{max}\propto\frac{1}{T}$? If you set \begin{equation} u(\lambda,T)=\frac{f(\lambda T)}{\...
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What is the wavelength of gravitational waves?

What is the wavelength of gravitational waves? I have looked for an answer but so far not identified one.
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Refractive index and wavelength relation [duplicate]

In general, the refractive index of a certain medium tends to decrease with increasing wavelength. But are there any materials in which the opposite phenomenon occurs? That is, in which the ...
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Why are line spectra only seen in gases?

This might be a stupid question but I could not find the answer in my textbook or on the internet with a few searches. So I believe when an atomic electron moves down to a lower energy level it ...
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3answers
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Does the mass of photon affect its size or vice-versa?

Does the wavelength of photon affect its size, as when the wavelength is big the photon has big size and it small it has small size? In the electron microscope the electron should poses a small ...
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409 views

Planck's Form of Wien's Distribution Law

Can anyone explain how Wien's distribution law seen in Wien's original "On the Division of Energy in the Emission-Spectrum of a Black Body": $$ \phi_\lambda = \frac{C}{\lambda^5} e^{-\frac{c}{\lambda ...
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What are the other ways to pass particular wavelength of light without using optical band pass filters?

I'm working on an experiment that have visible spectrum light source (RGB LED at e.g. 495–570 nm wavelength), holder with sample, narrow bandpass filter (eg: CWL:520nm, FWHM:5nm) and a photodiode to ...
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What do the Bessel & Brett, Buser & Kurucz and Cousins filters evolution with time tell us?

I have been studying different filters to observe galaxies and I'm not sure I completely understand what information one can take from, in particular, the evolution of difference of intensity in the U-...
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What is considered a wavelength?

What is considered a wavelength? I am getting confused here. I keep seeing one wavelength is the distance when the wave repeats itself. So at the two highest points that's the wavelength. Now I'm ...
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583 views

What's the longest wavelength single photon we've ever observed? [duplicate]

At short wavelengths, our light detectors tend to be photon counters (e.g. CCD light sensor). At longer wavelengths, we use antennas and bolometers that tend to add up energy instead of counting ...
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Can molecule displacement when increasing the amplitude be larger than a wavelength of a given sound?

I don't understand how these two quantities (amplitude + wavelenght) are not directly related to each other. If my understanding is correct amplitude is displacement thus distance, same as wavelength....
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Why and how are wave sets (groups) created?

At a coasts wave normally arrive in groups (sets) and we wondered why this is the case. Some internet research did reveal some clues but no convincing answer. I want to know why waves gather in ...
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Why do quantum effects of gravity become important at the Planck scale?

The standard heuristic argument for why quantum effects of gravity become important at the Planck scale is to consider the length scales at which both quantum field theory (QFT) and general relativity ...
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Is a purely white light made up of an equal amount of all wavelengths of light in the visible spectrum? [duplicate]

I've heard that a blackbody radiator at 6500 K, for instance, emits pure white light, but does that mean it's made up of all wavelengths in the visible spectrum in equal proportions? Or is the ...
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is current flow in open circuit with wire length=λ? [closed]

if ac source connected to resistor in open circuit as shown below: each wire length =λ/2(suppose wire resistance is zero) is current flow?
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Is the decrease in wavelength proportional to the reduction in speed?

I conducted a small at home experiment where I compared a red laser’s wavelength through water vs air. I put a diffraction grating in water and then did the same out of water. See photo It was ...
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Blackbody radiation, de Broglie equation, and lightwaves to be shifted left

I'm having a hard time figuring this out. Say we heated a lead ball to 1,000 Kelvin. Not all of the particles are at the exact same temperature--some parts are a little hotter, some are a little ...
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Is there any quantum mechanics process in a prism?

Red light has longer wavelength than say blue light and so bends the least as it travels much faster in the same medium. My question is since energy is not stated in the above explanation, is QM ...
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347 views

Doppler shift and speed of rotating objects in space

I understand the concept of how we can use the doppler effect to know if an object is spinning, in the sense that the part of the object spinning towards us will exhibit a blueshift, and the part ...
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289 views

Why does energy loss cause end corrections?

Several people have said that end corrections occur because of acoustic radiation or something similar, where energy is used in vibrating the air outside the pipe. How exactly does energy loss cause ...
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889 views

How is the relationship between the end correction and the pipe diameter related to acoustic impedance?

I know that Levine and Schwinger calculated the exact value of the end correction by doing something with the acoustic impedance but I don't understand their calculations. I've looked at paisanco's ...
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2answers
136 views

Standing waves of a string

Why standing waves cannot be form from every frequency but only a particular frequency? I understand standing waves as a pattern that will be formed from one wave interfering with another, but i dont ...
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3answers
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Problem in grasping wavelength of light

I am having a problem grasping the concept of wavelength of light. We define wavelength as the minimum distance between two particles of a wave vibrating in the same phase , but in case of light there ...
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Is Color Temperature and Wavelength the Same Thing?

I know that a higher color temperature is associated with cool light and a lower color temperature is associated with warm light (green and red) However I'm trying to understand the correlation ...
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Deriving relativistic Doppler shift in terms of wavelength? [closed]

Consider a star moving with velocity $v$ at an angle $\theta$ with respect to its line of sight to Earth. Show that the relativistic Doppler shift is $$\lambda_{obs} = \frac{1 - \frac{v}{c} cos(\...
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Why does the speed of a wave travelling in shallow water increase in deep water?

Exactly as the title says. Why does the speed of a wave travelling in shallow water increase in deep water ?
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Planck's law: $B_\nu (\nu, T)$ to $B_\lambda (\lambda, T)$ [duplicate]

Wikipedia says that Planck's law is: $$B_\nu (\nu, T) = \frac{2h\nu^3}{c^2}\times \frac{1}{e^{h\nu /(k_BT)} - 1}$$ So, to convert this to wavelength, I substituted $\nu = \frac{c}{\lambda}$ which ...
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Compton Effect (graph between relative intensity and wavelength)

Why is the peak of the graph more for greater wavelengths? Since wavelength is inversely proportional to energy and relative intensity, shouldn't the peak for greater wavelength be lesser? Please ...
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2answers
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Traditional derivation of photon momentum $p=h/\lambda$ is suspect?

Taking that the energy of a photon is $E = hf$, plugging into the energy-momentum relation yields $$(hf)^2 = (mc^2)^2 + (pc)^2\\ p = \frac{h}{\lambda} $$ Was this operation valid? I ask because $E ...
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182 views

“Tangential” blue-shift: train with light on side passing parallell to observer

I have the following problem: "A blue light, emitting at a wavelength $\lambda = 400 (nm)$ in its rest frame, is mounted to the side of a train traveling at a constant speed of $v = 0.6c$ in a ...
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Light and transparency

As we know, light is reflected by a mirror, so we can see our image, it is mostly reflected by a white wall (that does not get hot) but we cannot see our reflection, it is absorbed by a black wall, ...
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How could I measure the colour spectrum of a light bulb and investigate how closely it matches a black body radiation curve?

Here is my research question: What is the colour/spectrum produced by each globe type? What is the temperature equivalence? How closely does a globe match a black body radiation curve? I will be ...
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How can a wavelength be defined for a laser where a photon's travel distance over a pulse duration is less than a wavelength?

Femtosecond laser pulse are widely used in experimental physics. Femtosecond lasers like Nd:YAG systems produce coherent light at wavelength 1053nm. The distance traveled by a photon in 1 fs is 300nm; ...
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Proof of de Broglie wavelength for electron

According to de Broglie's wave-particle duality, the relation between electron's wavelength and momentum is $\lambda =h/mv$. The proof of this is given in my textbook as follows: De Broglie first ...
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Wavelength-division multiplexing (WDM) and white light spectrum wavelengths differ

I am a newbie to Optical fiber communications and was going through the article on WDM on wikipedia here: WDM Wikipedia I also went through the below article on prism diffraction of white light into ...
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533 views

Relationship between Wien's law and Stefan-Boltzmann's law

I'm studying Quantum mechanics by Bransden and Joachain and in the introduction chapter it says: Wien showed that the spectral distribution function had to be on the form $$\rho(\lambda,T)=\lambda^{-...
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What is the wavelength of electrical current?

I am trying (as an exercise) to determine the force between two wires, in a similar nature to this question here. This suggests a solution based on the wavelength of the wave. However, the ...
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112 views

Will a reflection phase change work regardless of wavelength?

If I have a gamma photon traveling in air and it shoots off towards a glass mirror and bounces off it, when I measure its phase, will it have changed by 180${}^\circ$? I was reading the wikipedia ...
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Will overlapping two different beams of coherent light with different wavelength cause interference?

If I use two different wavelength lasers to transmit light into a single mode optic fiber will they interfere with each other? If so, how much will be that interference.
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The color of a refracted ray

My textbook explains the cause of the refraction of light as the "difference between the speeds of light when passing from medium 1 to medium 2". The same textbook explains that the cause of the ...
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489 views

Phase of a plane wave is an invariant quantity

As described by Jackson's Classical Eletrodynamics [1], the phase of a plane wave is an invariant quantity for all coordinate frames. Jackson justifies this statement using the fact that the phase of ...
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Filter for RGB separation

Looking at Bayer filter of a typical consumer camera, one can easily see that sensitivity of the filter for each color is all over the place. Are there filters similar to Bayer that do a better job at ...