Frequencies Definition and 412 Threads

Say I have ranges: (-infinity to 16) where the observed frequency is 35 (16 to 18) where the obs freq is 100 (18 to 20) where the obs.. freq. is 360 (20 to 22) where the obs. freq. is 326 (22 to 24) where the obs. freq. is 150 (24 to infinity) where the obs freq is 29 The mean is 20...

Homework Statement I'm trying to solve an example in Boas's book (Mathematical methods in the physical science page 423) but by using Goldstein's (Classical mechanics) method. The mechanical system consists of 3 springs (with constants k) and 2 masses (with mass m) this way: |----m----m----|...

Hi people, we were doing an experiment in lab where we excite a plate clamped at the circumference at various frequencies to detect natural frequencies. My questions are: 1. Sometimes at certain frequencies, we were observing multiple mode-shapes (an overlap of two mode shapes, to be exact)...

Homework Statement I'm working on a problem that involves solving for the eigenvalues and the natural frequencies. I've attached my work as a pdf file and also the MATLAB code used to get the result. The problem that I'm running into is that the frequencies computed from the determinant are...

Homework Statement A particular guitar string is supposed to vibrate at 217 Hz, but it is measured to actually vibrate at 222 Hz. By what percentage should the tension in the string be changed to get the frequency to the correct value? Do not enter units. Homework Equations...

I have a question. If you have two light beams of different frequencies, would you observe interference fringes?

Trying to figure out how to go about solving this question, using these forumlas i tried to solve it but i didnt get the right answers for frequency 1 i went with f1=v/2L for frequency 2 i went with f2=v/L any ideas on how to solve this?

I understand it's possible to cross two ultrasonic frequencies one with sound modulating in it possibly in ssb format to recreate the original sound at the point the two cross. I think someone is using this trick to harass me. The sound appeared to be on the other side of a party wall at first...

[b]1. A person standing close to a railroad crossing hears the whistle of an approaching train. He notes that the pitch of the whistle drops as the train passes by and moves away from the crossing. The frequency of the distant approaching whistle is 555 Hz; it drops to 472 Hz after the train is...

Hi everybody, this is my first post here :P I'm currently struggling over a weird problem, which asks for the amplitude (eg, max value) of a sum of many waves with different frequencies. eg, max value of \sum_0^N {A_i cos(w_i t + \phi_t)}

Hi, I'm trying to understand vibrations and specifically what happens in the natural modes of frequency.. 1. It seems that the harmonic nature of solution(with Acos(wt)...where A is the amplitude) applies only in the natural mode of vibration...and so the system will have a defined mode...

Alright, my previous thread on this I stated this question incorrectly and it was removed. Ok so I'll rephrase it and try and make it all spiffy so it follows the site's guidelines ;) I've looked up a lot of things in regards to phase-space, but I'm still a bit foggy on how it all works. I'm...

Hi All, I have a component that at 1 Khz has 100 mH Inductance and 100 Ω resistance. I know that at higher frequencies which I will need to run the circuit, these values won't be the same anymore. Is there any way, mathematically, to figure out what those values would be at higher...

Is it true that by finding exact resonant frequency we could ionize matter or split molecules? What is frequency to split water molecules into H+ and HO- ions? What is resonant frequency to split up hydrogen atom into proton and electron? Would spliting water molecule require less energy...

Homework Statement Δp = (1.3 Pa) sin π[(3.00 m^-1)x - (300 s^-1)t]. Is the pressure of a wave. Find frequency Homework Equations The Attempt at a Solution Angular frequency = 300s^-1 = 300 hertz. Frequency = angular frequency / 2pi = 47.746 Someone, please explain...

How can we calculate the vacuum fields corresponding to certain frequencies?

Homework Statement ***This is problem 11.29 in Taylor's Classical Mechanics*** A thin rod of length 2b and mass m is suspended by its two ends with two identical vertical springs (force constant k) that are attached to the horizontal ceiling. Assuming that the whole system is constrained to...

Hi, Which frequencies does an MRI machine use? Is it microwaves? Would prolonged exposure to it be damaging to the body?

Hi, I have 2 coils arranged next to each other. One of them is used to generate alternating magnetic field at several Hz, and the other one also generate alternating magnetic field but at higher frequency (several kHz). Are there any magnetic sensors that can measure only the...

there is a parallel R - C circuit connected with a alternating current source of frequency 'w'. on plotting the function of |z| vs 'w' we get max at w=0; and max/2 at 'w'= 1/RC. while calculating power absorbed by resistor, we get Pmax = 1/2I^2R( >>>? how).. and at w = 1/RC power by resistor...

Homework Statement You find an abandoned mine shaft and wish to measure its depth. Using an audio oscillator of variable frequency, you note that you can produce successive resonances at frequencies of 83.72 Hz and 107.64 Hz. What is the depth of the shaft? Assume the temperature in the...

Homework Statement A string is stretched between fixed supports separated by 82.0 m. It is observed to have resonant frequencies of 334.000 and 389.667 Hz, and no other resonant frequencies between these two. A)What is the lowest resonant frequency of the string? B)What is the wave...

Question: 8 phenotypes were observed as a result of a trihybrid cross. The frequencies of the phenotypes are a+ b+ c- = 570 a- b- c+ = 545 a+ b- c+ = 17 a- b+ c- = 20 a+ b- c- = 140 a- b+ c+ = 128 a+ b+ c+ = 65 a- b- c- = 61 No other information is given. It is not even specified if...

1. Homework Statement Write a wave in one space dimension as ARe(ei(kx-wt-d))where A is the amplitude of the wave. Find a second wave of the same frequency such that the sum of the two vanishes at x = 0 and x = L. Assuming the wave velocity c = w/|k| is fixed, for what frequencies ! is...

When I shine two different lights at a single spot on a white screen, say, yellow and blue, they both hit the spot and get reflected all mixed up and I see green. Thats all fine, but what is the actual structure of that reflected, in this case, green light? Is it a ordinary green photon with its...

My book reads step 1 = 2 cos(654πt)cos(-130πt) step 2 = 2 cos(2 * 327 * π * t)cos(130πt) step 3 = f2 - f1 = 392 - 262 = 130 Hz t = seconds π = pi I don't see how they get from step 1 to step 2, nor do I understand how they get from step 2 to step 3.

Why does an atom emit discrete frequencies of light? Solving the Schrodinger wave function for the hydrogen atom (that is a single particle representing an electron bound by a spherical potential) we find that it has discrete energy levels. Plotting every possible value of f in E'-E = \hbar f...

Hi - I'm new here - I'm just writing a paper based on an acoustical analysis of a rock/pop performance venue in a college I work at, and I'm up to my uncertainties section. I've read up on uncertainties, and feel confident in working out uncertainties for simple additions, multiplications...

At high school currently doing a unit on sound waves and frequencies. Any suggestions on experiments/investigations we could look at. We have microphones, speakers, guitars, strobe lights... Any Suggestions?

Our high school unit is looking at sound waves and frequencies and we are looking for some suggestions as to what experiments/investigations we could run? We have speakers, microphones, guitars, strobe lights pluss more to use, What are some ideas we could look at?

¿ Can diff. EM frequencies create diff. magnetic fields with diff. properties ? I understand that a magnetic field is generated via moving charged particles . Electricity and magnetism are linked through electromagnetism . Electromagnetism can be in different wavelengths and frequencies but...

¿ Magnetic Frequencies ? I understand that a magnetic field is generated via moving charged particles . Electricity and magnetism are linked through electromagnetism . Electromagnetism can be in different wavelengths and frequencies but does this mean that magnetism and magnetic fields are at...

Homework Statement A tunning fork with frequency f = 512 Hz is held by someone who swings it vigurously in a circle in the horizontal plane. The radius of the circle is 1.0 m, and the frequency of revolution is 3.0 rev/s. (a) What are the max and the min frequencies that a second person...

Hello. I've made a lab experiment of interference and with a CCD camera photographed fringe pattern which one can understand as a periodic signal. My question is: When I apply an FFT to the image is there any limit to the amplitude information I may get from lower frequencies? I read in the...

I am trying to read high frequency signals (as in, tens to hundreds of Megahertz) from a magnetic tape. I figure the original preamp will be unable to function anywhere near that range. So, I am trying to find a way to replace it. I have yet to get an operational amplifier to work. I keep...

I know that all bodies with a temperature above absolute zero radiate energy away as the following. P = AeσT^4 However, I wanted to know how you could find the frequency of the power being emitted just by knowing the temperature. For example, how would I find out how much heat I need to...

Since the old topic is locked, I had to post a new one about this (old topic here: https://www.physicsforums.com/archive/index.php/t-231156.html" ) People were talking about resonant frequencies for body parts and/or the entire body and someone was looking for a chart, not sure if this is...

I'm brushing up on my knowledge behind the physics of NMR. Turns out there was a lot I had misconceptions about; I thought it was very similar to absorbance/transmittance spectroscopy. I read some material about it which threw that idea out the window. I'm now looking at a video that shows a...

A violinist places her finger so that the vibrating section of a 1.0g/m string has a length of 30cm, then she draws her bow across it. A listener nearby in a 20 degrees celcius room (speed of sound at this temperature in air is 343 m/s) hears a note with a wavelength of 40 cm. What is the...

Homework Statement An ADC system samples at frequency of 500Hz. it is preceded by 4-pole low_pass Butterworth filter having a 3db frequency of 1KHZ. Three intefering signals are present at frequencies of 2kHz,2.6kHz and 4.4kHz a) what is the Nyquist frequency of the process? b) what will...

if a free-free bar has a crack located somewhere along it's length, in order to find the natural frequency of the bar do you split the bar on either side of the crack and assume each bar is free/excited? What would the equation for natural frequency be in this situation?

I would like to ask a few questions. Does a table of refractive indices of materials at rf frequencies (say for TV) exists? Is there a way for me to estimate it for some materials? Are the refractive indices of these materials higher? Will those materials have low absorption losses at these...

Homework Statement in the 1st lecture of DSP in the college the prof. tells us that in sinusoidal signals such as sin (wt) the (w) is the analog freq. in time domain but if it was a discrete signal (not continuous) such as sin (wTn).. wT will be the digital freq. I'm really confused and...

Homework Statement Model the above beam with 3 elements(image provided in attachment). Calculate and list the first 6 natural frequencies Plot the mode shapes corresponding to each of the natural frequencies Homework Equations DET(M^{-1}*K + [I] \omega^2)=0 shape functions...

Homework Statement The following is the output of a 16 point computation of the discrete Fourier Transform for data taken at 10 kHz. Complete the table below by determining the frequencies associated with each of the FFT values. I attached an Excel workbook with the table. Homework...

Homework Statement When a particular inductor and capacitor are connected across the same AC voltage, the current in the inductor is higher than in the capacitor. Is this true for all frequencies? Homework Equations Current through a capacitor Ip=(Vp)(2pi)(f)(C) Current through an inductor...

Homework Statement Given the network transfer function H(s)=10s/(s^2+300s+10^6) Find the center frequency, lower and upper half power frequencies and the quality factor Q. Homework Equations Beta=R/L (omega naught)^2=1/(LC) BW=hi-lo=R/L H(s)=(R/L)s/(s^2+(R/L)s+1/(LC))...

my understanding is that energy is wasted in a solar cells when light with more frequency than necessary to make an electron cross the band gap comes along and the excess energy is converted to heat. does this mean if you only shined blue light at a solar cell which had a perfect electron gap...

Homework Statement A radar antenna broadcasts electromagnetic waves with a period of 0.171 ns. What range of frequencies would need to be superimposed to create a 1.71 ns long radar pulse? Homework Equations f=1/T v=fλ The Attempt at a Solution I just couldn't understand what the...

Homework Statement The band levels for a noise are 70 dB reference 20\muPa at 31.5 Hz and decrease 3 dB for each octave. Find the overall sound pressure level between 31.5 and 8000 Hz and the A-weighted sound pressure level for this frequency range. Homework Equations...