Frequencies Definition and 395 Threads

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----|...

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 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...

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...

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 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 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...

Hi everyone, So, resonance, are resonant frequencies and natural frequencies the same thing with a different name? If not could someone please explain the difference. Been searching for the answer for over an hour. Thanks in advance Peter

I am a piano teacher with some very cool, science-minded students. Usually we stick to basic acoustics, and mechanics in terms of piano technique, but yesterday one of them took things in an interesting new direction. . . he described to me how, when he closes his eyes and listens to the music...

Assuming a flat pane of colored glass, using colored lights... If you pass red light through red glass, will it be blocked? How about if you pass red light through a green glass- What will the color/frequency of the light which passes through the glass be? Would you simply add the frequency...

If I am correct, crystal frequencies depend on the size, shape/cut, and purity of a crystal(?) How can you measure (what instrumentation) the frequency/ies of a natural crystal (other than just quartz)?

Hi Say I have a real quantity given by x(t) = \int_{ - \infty }^\infty {\tilde x(\omega )e^{ - i\omega t} d\omega } Now I complex conjugate it (remember it is real) x(t) = \int_{ - \infty }^\infty {\tilde x^* (\omega )e^{ + i\omega t} d\omega } How is it that I from...

Homework Statement 1)A stretched wire vibrates in its first normal mode at a frequency of 383 Hz. What would be the fundamental frequency if the wire were one fourth as long, its diameter were quadrupled, and its tension were increased four-fold? 2)A 0.0125 kg, 1.88 m long wire is fixed at...

Hi, I am wondering what sort of frequencies electrons have in atoms at different energy levels. When I say frequency, I'm *not* talking about the frequency of the orbiting motion. I am wondering what the electron wave oscillation frequencies are at the different energy levels. A couple...

Hi In (quantum) optics, many authors state that the field amplitudes satisfy E\left( { - \omega } \right) = E^* \left( \omega \right) But how is it that one can prove that this is correct? I have never seen any book do this,

For an assignment (not really homework, but not really exciting either), I'm trying to calculate the total entropy for the reaction: Na2 + X2 \rightarrow 2 NaX Where X = F, Cl, and Br . ( I told you this isn't exciting). Also, in this theoretical reaction, everything involved is an...