Spectrum Definition and 765 Threads

As I understand it, there are these categories: radio microwave infrared light visible light ultraviolet light X-rays gamma rays It seems that microwaves are really just radio waves that happen to have a very short wavelength, with the distinction that radio & microwaves are waves...

Hi I have read the following online (http://tf.nist.gov/general/pdf/1819.pdf): "Regardless of the application, the basic goal of locking the frequency of a laser to a cavity is to reduce the frequency fluctuations between the laser and cavity. The noise spectrum of the laser’s frequency...

Wikipedia showed me the solar spectrum during the day: http://en.wikipedia.org/wiki/File:Solar_Spectrum.png I imagine its very different at night, however is everything 0? Is there any residual black body infrared radiation?

Hello! I am doing a thesis in ecology using a two dimensional binary cellular automata. I have sampled a parameter for a number of generations and I would like to calculate the power spectrum for this data. I had been planning to use a software for this, but now it seems I have to do it...

Hello everybody, (sorry for the eventual Engrish) I can't find any convincing answer for the following question : Why do we always (or often) plot the CMB power spectrum in this way : jb.man.ac.uk/research/cosmos/vsa/images/CMB_power_spectrum.gif I mean the y-axis is $$C_\ell \ell...

A gas of a hypothetical atom in ground state (-14eV) is irradiated with photons having a continuous range of energies between 7 and 10 electron-volts. Photons of which energies will be emitted from the gas?The energy levels look like this: 0-------------------(ionization state)...

Does anyone know the difference between the power spectrum of a signal and the power spectral density (PSD) spectrum of a signal? I've read on the net lots of things ranging from: i) They are identical ii) Power spectrum is units of Watts, power spectral density spectrum units of Watts/Hz...

Would like to see if I've understood this question somewhat. :-) Homework Statement A doubly ionised Lithium atom (Li^++) has two of its normal complement of electrons removed. The energy levels of the remaining single electron ion are closely related to those of the neutral Hydrogen...

I know that an AM Amplitude vs. Frequency Spectrum has a central frequency = carrier frequency and two side bands of carrier frequency ± signal frequency. Now what would a similar spectrum look like for an FM wave ? My textbook just says that '... further side frequencies that are...

I was working on calibrating some newly purchased software onto our lab computers when I noticed that the decay spectrum on the screen did not look exactly as it does on published material. I attribute this to background radiation effects (correct me if I am wrong please), so I decided the best...

Could anybody explain what "power spectrum" in cosmology means. I am trying to understand the WMAP power spectrum graph, in particular. For example, what do the multiple moments physically represent? The graph is here: http://casa.colorado.edu/~ajsh/cosmo_04/wmapcl.html

What is the source of sunlight? The answer is Solar spectrum. Can anyone explain how the crimson color is created? actually what happen when the sunlight is created? Need help from the expert.

If A is a bounded operator on a Hilbert space H, isn't the following true of the residual spectrum \sigma_r(A): \lambda \in \sigma_r(A) iff (\forall \psi \in H, \psi \neq 0)((\lambda - A) \psi \neq 0) iff \ker (\lambda - A) = \{0\} iff \lambda - A is injective? So isn't the condition that...

Hello I have this Hamiltonian: \mathcal{H} = \alpha S_{+} + \alpha^{*}S_{-} + \beta S_{z} with \alpha, \beta \in \mathbb{C} . The Operators S_{\pm} are ladder-operators on the spin space that has the dimension 2s+1 and S_{z} is the z-operator on spin space. Do you know how to get (if...

Is it possible for EM radiation to exist outside the EM spectrum? I'm aware of the different frequencies at which energy can be radiated eg. radio, infrared, and gamma. But is it possible for objects to absorb or release energy at subradio or supergamma frequencies? Or is there a physical law...

Hey guys, I recently noticed that, after a swim, when you look at the light, you see a spectrum around it. The light was white light. And you see it with naked eyes. Can you guys explain this phenomenon? The water did contain Chlorine and maybe other necessary chemicals required in...

so the title speaks for itself i hope. my problem is i don't know how to work the formula. what are the ns about?? lamba^-1 = R(n1^-2 - n2^-2)

Dear All I am trying to measure the spectrum of an incandesant 6V 15W tungsten microscope lamp. I have a reasonably old scanning monochromator (diffraction grating based) coupled to a fibre optic cable and it has given me the spectrum...

This question might be better answered by someone in the mobile industry, but I guess I'll ask it here since it does involve physics. I understand that wireless spectrum for mobile data is finite, and will run out at some point. Out of curiosity, what are the implications of that exactly...

Homework Statement Let A be a linear transformation on the space of square summable sequences \ell2 such that (A\ell)n = \elln+1 + \elln-1 - 2\elln. Find the spectrum of A. 2. The attempt at a solution I see that A is self-adjoint, so its spectrum must be a subset of the real line. We also...

I was taking solar spectra yesterday for a Physics lab, and I found this strange phenomenon slightly to the left of the sun. I think it might be a solar prominence, but then again I know absolutely nothing about astronomy. What is it? (The graph is intensity vs. wavelength)...

hello i was just wondering what is considered to be the finger print region in an IR spectrum. Is there a range of wavenumbers which are designated as the finger print region? ...let me clarify um so a C-O bond in an ether (and maybe alcohol) is suppose to have a peak in the 1000-1200cm^-1...

Homework Statement (a)The cosmic microwave background fits the blackbody radiation spectrum well with a temperature of 2.7 K and a corresponding peak wavelength at 1.9nm. Applying the relationship between the radiant emittance, i.e. the total power emitted per unit area, and the photon energy...

Hi The new edition of th book " fast Breeder Reactors" by Reynolds has been revealed by the Springer publishing under the title of " Fast Spectrum Reactors". the book is downloadable in the following address for those who have access to Springer accounts...

Homework Statement I need help assigning the peaks in a Raman spectrum of acetylene(ethyne). The peaks are : Wavenumber Contours 3372 OQS 1973 OQS 613 OPRS 2. The attempt at a solution Ethyne has 7 vibrational modes (...

Homework Statement I have attached the question and necessary infromationHomework Equations The Attempt at a Solution so here's what I would say "Unlikely as the peaks in the IR spec are very similar, no additional peaks have shown" BUT THE MARK SCHEME SAYS Vanillin IS likely to have...

dear all, after doing a complex Fourier series on a function. i am asked to find and graph the magnitude and phase spectrum of a function. now to cut the long story short. let's say we arrived a Fourier series like this. = \sum_{i=-∞}^{∞} \frac{1}{npi}sin...

I got this thing from wikipedia: http://img72.imageshack.us/img72/9878/vlszo.jpg Link to wikipedia: Visible spectrum So: - Is it the right scan of visible spectrum? Because when I search, there are a lots of other version, which is not really like each other. (Google Link) - What is the...

how can microwaves heat food?

Homework Statement X rays give continuous spectrum and line spectrum. Whether these spectrums are emission or absorption spectrum? Homework Equations The Attempt at a Solution I think it is emission spectrum, because there is no absorbing material. Still, i need confirmation from...

What determines the wave length.

I've recently taken a spectral image (visible wavelengths) of Jupiter. After calibrating my spectral analysis program I've been able to get wavelength per pixel and produce a graph of intensity vs wavelength. I have an absorption spectra of Jupiter, but I am unaware on how to correlate which...

Hello! I'm writing a thesis about the optical properties of CO2. However I'm having a hard time finding any solid material about the basic info of the absorption spectrum of CO2. I'm especially interested in the absorption band at approximately 4,3µm. If any of you guys know some good articles...

Hi there, just wondered if anyone could help me... If I am given a hamiltonian describing a particle in one dimension H=p^2/2m +1/2 (γ(x-a)^1/2) + K(x-b) how do I go about finding the eigenstates and eigenvalues of this hamiltonian? Many thanks

hi i was wondering why the spectrum of an ordinary light bulb is continuous. i know that "i think it's thermodynamics" says that some temperature creates a specific continuous radiation, but how is this reconcilable with quantum mechanics and e.g. a sodium gas, that emits only a tiny yellow...

[Solved] How and why does a prism split white light into the colour spectrum Homework Statement How and why does a prism split white light into the colour spectrum? Homework Equations Red light has a lower frequency than violet light. As speed of light = wavelength * frequency, red...

I'm trying to calculate the mass of a chemical (DMSO) and from a NMR spectrum of water and DMSO. I have the value of the total area under the spectrum and I have the value of the total area corrosponding to the DMSO peak and the total area corrosponding to water. I know that the total area of...

Hi, I've been trying to figure out how to convert a spectrum from wavelength space into velocity space. I thought it would be a simple relation, but I can't see it - maybe I'm missing something? I've got Flux v Wavelength at the moment, so I converted into frequency space. I've played...

Homework Statement A two-state system has Hamiltonian \sum |i\right\rangle hi \left\langle i| + Δ (| 1 \right\rangle \left\langle 2| + |2 \right\rangle \left\langle 1 |) Where, \left\langle i | j \right\rangle = \deltaij, hi, and Δ are real. Compute the energy spectrum of this...

I know that light is a form of electromagnetic radiation but I know that all electromagnetic radiation is not light. I know that light has four basic properties: 1) Light travels in straight lines. 2)Light can reflect. 3)Light...

A question I have puzzled over for a year now is how we define time. We chose light as the fastest thing we know (currently) as our mathematical limit, as only massless particles can only reach c our calulations of Gr and Sr are based on this. Unitl I started hearing terms of backwards in time...

Is it a silly question to ask *why* we see the orders of colors the way we do in the visible spectrum with respect to wavelength? For instance, I know that comparisons to dogs are often made with the following visible spectrum comparisons...

Assuming, of course, that we simply rescaled our color perspectives so that longest wavelengths = red, shortest wavelengths = violet. Are there any such pictures?

Radiation with a wavelength in the visible light range is what mainly reaches the Earth's surface. What is so special about visible light that makes it so easy to reach the surface compared to something like gamma rays with a smaller wavelength or something with a larger wavelength? Also...

I am in need of the wavelength of the spectral lines of sodium but all I can find is the wavelength for the doublet. I am looking for the cyan coloured one that appears very close to 500nm but I cannot find the exact value anywhere. Would anyone be able to direct me somewhere? Thanks

Hi there, So I am doing this lab write-up at the moment with a single channel analyser. The following diagram pretty much sums up the setup: So pretty much I have found a suitable operating voltage gain by recording number of counts vs. gain and now I must change the Baseline-E...

Continuous absorption spectrum -- why this happens? Homework Statement A pure green glass plate placed in the path of light, absorbs everything everything except green, similarly red glass plate absorbs everything except red. Homework Equations May i know the reason for this? Thanks...

Homework Statement While dealing with continuous absorption spectrum, my book depicts like this " A pure green glass plate when placed in the path of white light, absorbs everything except green and gives continuous absorption spectrum" Homework Equations The Attempt at a Solution...

Homework Statement I have an autocorrelation function given by R(\tau) = J_0(2\pif_d\tau) I have already plotted it in Matlab using the following commands ts=0.0000001; fs=1/ts; fd=100; tau=0:0.0000001:0.05; R=besselj(0,2*pi*fd.*tau); How do I plot its PSD in Matlab and the plotted picture...

In wikipedia I've read that the Sun's surface temperature is about 5700K. The emission spectrum graph can be seen there: http://en.wikipedia.org/wiki/File:EffectiveTemperature_300dpi_e.png. I don't understand why the irradiance (or intensity I guess) of the Sun is greater than the one of a...