Spectrum Definition and 765 Threads

Homework Statement In a Franck-Hertz experiment carried out with potassium vapour, it is found that the current falls off rapidly at an applied voltage of 1.62V. Calculate the wavelength of the expected spectral line in the emission spectrum of potassium when this voltage is reached. Homework...

I just had the thought that atoms emit light at quantized levels but that would seem to imply that only certain energy levels could possibly exist instead of a complete spectrum. But, if light is traveling down or away from a gravitational field the frequency gets shifted. Would this make it...

What does a 180 degree phase shift of a sinusoidal in a signal do to the frequency spectrum of the signal?

Hi everyone! In amatuer radio, when we transmit on a specific frequency, we 'use' that frequency and depending on the power you "use' a slice of bandwidth around that frequency. So if two people transmit on the same frequency there's either a pleasant conversation, interference, or they'll just...

Homework Statement Find the Fourier spectrum ##C_k## of the following function and draw it's graph: Homework Equations 3. The Attempt at a Solution [/B] I know that the complex Fourier coefficient of a rectangular impulse ##U## on an interval ##[-\frac{\tau}{2}, \frac{\tau}{2}]## is ##C_k =...

Hi. Usually, the clarinet is presented as acting like a pipe system closed at one end, which only allows for harmonics that are odd multiples of the fundamental frequency. I used the app "SpectrumView" by OxfordWaveResearch to measure the following spectrum: Fair enough, the amplitudes of the...

I'm trying to find a good database of absorption or reflection spectra in visible light for pigments. I've found a wonderful database in this article: http://e-conservation.org/issue-2/36-FORS-spectral-database#CSV It's almost exactly what I needed Except I don't understand the data The...

I've been doing some spectrum extractions in IRAF, stellar and galactic, and I was wondering if anyone here had any ideas on how to tell if the extraction/calibration/etc went well? I have a bunch of finished projects but I'm not sure about how to tell if they're any good or not. Let me know if...

Hi everyone, I have an absorption spectrum that I obtained from a sample after radiation and I need to use the background sample as a reference, how can I do that using excel? what I did is subtract the radiated from the background spectrum then plot it, is that right? Thanks.

Hello Everyone, I have some thoughts about Planck's law. The graph describes the spectral density of electromagnetic radiation emitted by a black body in thermal equilibrium at a given temperature T. I think the absorption (or absorbance?) spectrum of an ideal blackbody should be a horizontal...

Homework Statement Consider the density perturbation smoothed with a Gaussian of scale ##\sigma##, ##\Delta_{\sigma}(\vec x') = \int d^3 \vec x \frac{e^{- \frac{(\vec x - \vec x')^2}{2 \sigma^2}}}{(2 \pi \sigma)^{3/2}} \Delta (\vec x)## Calculate the power spectrum ##P_{\Delta_{\sigma}}## of...

Why is the vertical axis in the CMB power spectrum usually chosen as ##l(l+1)C_l/2\pi## instead of simply ##C_l## ? The only answer I found come from this post on stackexchange, but the answer doesn't seem very complete. Anyone knows ?

we know the five spectral series of Lyman, Balmer, Paschen, bracket, and Pfund their wavelength and also the part of EM spectrum they fall in, my question is why do we neglect the 6th series in the spectrum? and in what part of EM spectrum the 6th series exist and what could be its wavelength...

Hi, I am trying to code ultrasonic transducer radiation in water using angular spectrum of plane waves. I am having difficulties in the sampling and fft. If anybody has an idea about this can you please help me out? I can paste the code once i get some response. Thanks for your help!

My question is divided into two: a. One of Hg spectral lines is a strong one, 253.7 nm, emitted by transition from 3P1 (triplet) to 1S0 (singlet). I'm afraid I don't read the 1st state right, since it says S=1 (due to 2S+1=3) & J=1, hence (?) L=0. However, P means L=1, isn't it ? What am I...

Homework Statement Hi, So we started sampling/sampling theorem, dirac delta, DTFT in a digital signal processing module and I'm kinda confused. I understand how to derive the following formulae but these two formulae are so different to each other that I don't understand why? We are first...

Hi, I am going into the field of astrophysics and I am going to make my career a hobby, too. I want to buy a telescope that can measure the spectrum with CCD (astronomical spectroscopy) in a range of several hundreds of light years (like the Big Dipper). Does anyone know where can I get it...

I'm reading Eisberg's Modern Physics and in it, in the atomic spectra chapter, he says: "We have been discussing the emission spectrum of an atom. A closely related property is the absorption spectrum. This may be measured with apparatus similar to that shown in figure (5-1) except that a...

Homework Statement How can I measure the frequency of a really quiet sound. The software I have only measures the peak frequency (so not the frequency of the sound I want to measure which is lower f). Homework EquationsThe Attempt at a Solution

I’ve been digging around trying to get at the physical basis for the black body spectrum. Say I have a neutral gas,non ionized. This has its own discrete spectrum. Are the mechanisms of line broadening the reason why we seek continuous spectrum in the back body curve? That’s question 1. No 2...

Has the spectrum of light that is reflected off planet Earth ever been measured from outer space? (In the same sense that we measure spectra of the light emitted/reflected from other celestial bodies in astronomy). If so, would it be possible that there could be dips in the spectrum resulting...

How to calculate the width of spectrum produced by a dispersive prism of a given apex angle and refractive index, of white light of given width incident on first face of prism?

Hi,I’ve heard of a technology that enables to measure the distance of a satellite to the ground station by using non-coherent spread spectrum. Can anybody tell me what’s the name of this technology?Senmeis

I have heard that whatever we know about stars experimentally is through only what we can see from its surface since the light from the interior is "hidden." However, when we look at the spectrum of a star, we do see absorption lines for heavy elements. I think the reason why that is is because...

I have a work assignment where I'm supposed to calculate the transmittance of blackbody radiation through liquid n-heptane, and I have data of the heptane's absorption coefficient on the wavelength interval from 2.6 to 15 micrometers (it has significant peaks at about 3.5 ##\mu##m, 7.0 ##\mu##m...

Homework Statement I have an equation to solve. See the attach pichture. I(r,φ,λ) = I0.sin(2πr/R).sin2(φ).(1/λ) where I0 , R are constants r,φ are cylindrical coordinates 0≤r≤R/2 : the cut is laterally limited λa ≤ λ ≤ λb : the beam contains a limited frequency spektrum where the shortcut for...

Homework Statement A 191Os nucleus decays via β- emission to an excited state of 191Ir at 171 keV. What is the maximum kinetic energy of the electron on the β spectrum? a) 0.134 MeV b) 0.143 MeV c) 0.171 MeV d) 1.859 MeV Homework Equations 191 Os = 190.960928u 191 Ir = 190.960591u...

Homework Statement The emission spectrum of an unknown element contains two lines - one in the visible portion of the spectrum, and the other, ultraviolet. Based on the following figure and what you have learned about Niels Bohr's model of the atom, account for the difference in energy between...

Hi there, I am also familiar with Hilbert spaces and Functional Analysis and I find your question very interesting. I agree that the Fourier transform is a powerful tool for analyzing LTI systems and diagonalizing the convolution operator. As for your question about whether the same can be...

Hello, I was wondering if it is possible to make a definite clear spectrum of a chemical using a glass prism. I have one at home and no matter how hard I try to get an emission or absorption spectrum, it just does not turn out. Can you help? Do I need to focus the light into one point or such...

Hi. In physics articles, they say that sun light is white, and contain all colors. But they show say that the Sun's atmosphere absorb light at certain wavelengths, causing the intensity of the light at this wavelength to drop and appear dark. And the absorption spectrum looks like this...

In a spectrum from an MCA (that is hooked up to a scintillator and PMT), does an increase in amplifier gain cause the peak to shift towards higher channels? I have a source and its really weak so while calibrating my detector, I had to turn the gain up way high to see a peak, but I'd preferably...

I learned that two lines in the emission spectrum of Sodium, namely ## D_1 ## and ## D_2 ##, are on the visible region of the spectrum. Can I obtain these lines from a Sodium vapour lamp? I want to use a prism to separate out the individual wavelengths, a no then use a photographic film to...

Can some one tell me how to generate following signal on LTspice XVII.. Thanks..

Homework Statement For our investigation, we used a diffraction grating spectrometer to observe the emission spectrum of mercury. We conducted the experiment in a pitch black room to avoid any unwanted light pollution, etc. Whilst conducting the experiment we observed a number of 'faint' lines...

I was reading that one of the successes of the Dirac equation was that it was able to account for the fine structure of some of the differences in the spectrum of the hydrogen atom. But the Dirac equation is about subatomic particles moving at relativistic velocities. But an electron around the...

In the visible spectrum VIBGYOR, there is no black colour.So, what do we percieve as 'black' ? Another of my queries is that when dispersion takes place there is a change in wavelength but not so in case of frequency. But they are related inversely. So, why does this happen?

Does white light contain only the wavelengths of visible spectrum (i.e only from 400nm to 800nm)?

Hello, I am trying to estimate transfer function of unknown LTI system, given output and assumed input as point process. I have measurement of output, while input, which is assumed to be point process, could be created synthetically using known times and amplitudes. My questions: 1. What is...

Why are only certain colors of the emission spectrum in Hydrogen visible?

The radiation of an atom was interpreted by time-independent schrodinger equation:electron was transformed from high energy level state to lower and emit a photon.Could we treat this process through a wavefunction ##{\psi}(t)##? Before emiting,the system's wavefunction is ##{\psi}(0)## and after...

Homework Statement There are four scan modes for tandem MS: Product ion, Precursor ion, Neutral loss scan mode and MRM. e.g. In MRM, the result of graph is Intensity versus time, but NOT versus m/z. What does the "time" in the graph refers to? Homework EquationsThe Attempt at a Solution For...

I understand the EM spectrum is made up of photons at different energy levels (wavelengths); where, the higher the energy level the shorter the wavelength. What I do not understand is how collectively photons are created at a range of energy levels that produce a contiguous EM spectrum. (When I...

The Wikipedia article https://en.wikipedia.org/wiki/Dark_matter says DASI first detected the CMB polarization, and CBI provided the first E-mode polarization spectrum with compelling evidence that it is out of phase with the T-mode spectrum. A footnote [48] leads to...

can be calculated using the following formula: 1/ λ = R (1/n2f - 1/n2i) Where nf and ni are integers that can have values nf = 1, 2, 3, . . . , ∞ and ni = nf + 1, nf + 2, nf + 3, . . . , ∞. Which of the following sets of integers give the wavelength of a line in the Balmer series? (Note: more...

Hi all, I'd like to know if there's a reliable tool that can measure UVA and UVB concurrently at regular interval and record it. Or if can't record, then at least can be connected to a computer or network and will send the readings at regular interval. or perhaps anybody can point me to a...

I am starting work on structural durability area for after treatment systems and deal with Random Vibration and PSD profiles quite often. However there are few fundamental questions about PSD profiles that I could not get answer to after a lot of search on internet. So finally decided to write...

12V, 50W, MR16 halogen lamp spectrum is measured as shown ('B') with our newly developed mini-spectrometer having resolution ~1nm. But in internet it was similar to 'A' (We don't know how much resolution spectrometer they've used). Could anybody let me know what exactly the spectrum look like...

What is the difference between amplitude spectrum and frequency spectrum? In signals and systems.

Hello. I was playing with functions one aftenoon until I got this one: f(x) = sin(tan(log(x))). I was just wondering whether that function (at least, until the part that it doesn't get too compressed) has the same shape (to say it somehow) as the Electromagnetic spectrum...