Frequency Definition and 1000 Threads

Frequency is the number of occurrences of a repeating event per unit of time. It is also occasionally referred to as temporal frequency to emphasize the contrast to spatial frequency, and ordinary frequency to emphasize the contrast to angular frequency. Frequency is measured in hertz (Hz) which is equal to one event per second. The period is the duration of time of one cycle in a repeating event, so the period is the reciprocal of the frequency. For example: if a newborn baby's heart beats at a frequency of 120 times a minute (2 hertz), its period, T—the time interval between beats—is half a second (60 seconds divided by 120 beats). Frequency is an important parameter used in science and engineering to specify the rate of oscillatory and vibratory phenomena, such as mechanical vibrations, audio signals (sound), radio waves, and light.

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  1. A

    Choosing a pulse capacitor, ESR vs reactance at frequency

    While going through the catalogues I started to wonder, typically lower ESR caps cost more, but if I need the cap for DC smoothing , to filter out unwanted AC ripple, then I put that cap across my DC rails +-. Now so far so good. It's ability to filter out the AC ripple will be directly related...
  2. S

    Automotive Amplitude based frequency response simulation in Abaqus

    Hi, I have inputs like displacement of a driving mechanism and then the frequency of concern . Displacement: 0.2 mm Concerned Frequency: 100 Hz I would like to evaluate a part with the input displacement applied to a node and not as base excitation. It can be sweep over the frequency range...
  3. C

    I Does dividing maximum frequency by sound frequency give accurate velocity?

    Hello everyone! I'm watching a Walter Lewin lecture and it seems to me at least that he is dividing maximum frequency of the sound by sound frequency of the transmitter to derive velocity of the transmitter, does this work? It seems that quantity would be dimensionless and velocity obviously...
  4. hilbert2

    I Error tolerant normal mode frequency

    If a Hookean spring-mass system is made from one mass and a spring, to produce a system with a particular oscillation frequency, it's not a problem to use the propagation of errors concept to find how this frequency responds to small errors in the mass and spring constant. If a chain of...
  5. N

    Calculating Doppler Frequency Shift for Ultrasonic Waves

    Answer;
  6. Philip Koeck

    I Phase velocity and frequency of a matter wave

    The relationships for matter waves are (see e.g. https://en.wikipedia.org/wiki/Matter_wave): λ = h / p and E = h f, where E = m c2 From this the phase velocity can be derived and we get vph = c2 / v. v is the group velocity, which is also the velocity of the particle. If I consider these...
  7. EmmanKR

    Finding the Frequency Domain and Time Domain magnetic field

    I was wondering if anyone could walk me though a better explanation on how to get the given results for these two questions. The solutions posted by my professor aren't really clear to me so if anyone is able to better explain how to get the solution it would be much appreciated!
  8. S

    Angular frequency of a mass performing SHM

    When given a small displacement ##x##, the equation for m is: (i) N sin θ = m.a where N is the normal force acting on the ball and θ is angle of the ball with respect to vertical. (ii) N cos θ = m.g So: $$\tan \theta = \frac a g$$ $$\frac x R = \frac{\omega^{2} x}{g} \rightarrow \omega = \sqrt...
  9. Callum Plunkett

    Engineering Half-power cut-off frequency and frequency and phase response.

    I have been given the attached following question: FIGURE 2 shows the response of a first-order filter to a step input. Estimate the half-power cut-off frequency of the filter and sketch its frequency and phase response. I believe that I have correctly calculated the half-power cut-off...
  10. A

    I Deriving Doppler Effect Frequency w/ Stationary Person & Moving Source

    Can you derive the formula for frequency observed from doppler effect with stationary person and moving sound source away from the person like this: ##v_t = v + v_s## where ##v_t## is the total velocity observed by stationary person from moving sound, v is velocity of sound and ##v_s## is...
  11. DaveC426913

    B Frequency of Gravitational Waves: Limit & Possibilities

    A question elsewhere got me thinking about the frequencies/wavelengths of gravitational waves. The most obvious source of gravitational waves we are finding is from merging black holes, so presumably the orbital period will directly determine the frequency of those waves, yes? So the...
  12. benagastov

    Spectral Intensity Formula by Using Frequency

    I found there is kind of solution in Pointon's book: An Introduction to Statistical Physics for Students. But I don't know how to find intensity by using frequency.
  13. ace130

    Frequency Response Problem for given system

    Hello, I am given an exercise in which I need to answer some questions, for this given system : y(n)=1/3[x(n)+x(n-1)] 1/ find the impulse response h(n), then H(n) 2/ calculate the magnitude ||H(n)|| and tell the nature of the filter 3/ calculate Fc which is cutoff frequency when Fe=8Khz , and...
  14. D

    I Sound Frequency & Pipe Wall Thickness

    We have 2 open metal tubes, made of Stainless Steel. They both are the same length of 1 metre, and and Outer Diameter of 76mm. One pipe has a wall thickness of 1.5mm, and the other has a wall thickness of 2.0mm. It was our reasonable guess that the tube with 2.0mm wall thickness, should...
  15. samy4408

    B Question about electromagnetic waves -- Penetration vs. Frequency

    I read in a book that high frequency electromagnetic waves are more able to penetrate than low ones , so why radio waves can penetrate walls when light cannot?
  16. V

    Same frequency sounding different

    I was always thinking that frequency decides the type of sound we hear ( ex: high pitched squeaky sound). But then I read somewhere that loudness i.e. intensity can also affect the sound we hear. Still the quality of sound should depend only on frequency since loudness would simply make it more...
  17. penguin46

    Frequency of Oscillations of a Bead Resting on a Gas

    Hi, this is a question from my textbook that I can't quite make sense of. I don't really know where even to begin, to be honest. The only thing I can think of is that the bead is at equilibrium, thus the force of gravity is equal to the pressure exerted by the gas. I don't know where the heat...
  18. A

    Inverting op amp frequency response Bode plot help

    Using analog discovery 2 kit and the bode plot produced by the network analyzer is off. The scope looks fine and everything is behaving how it should except for the bode plot. The magnitude of the bode plot will start at the correct dB then right before tapering off it shoots up a few dB and...
  19. D

    I Frequency of EM waves in classical and quantum physics

    in classical physics, when a charged particle oscillates, it emits an electromagnetic wave, and the frequency of the wave depends on the frequency with which the particle oscillates. But in quantum physics, when an excited atom emits a photon, the energy of the photon depends on the magnitude of...
  20. B

    I Resonant Frequency Formula for a given object

    I know the v = λf is the formula to find the resonance frequency of a single continuous wave and the formula for resonance frequency of a spring is: 1/2π∗sqrt(𝑘/𝑚) but what about the Formula for a random object? a car, or a rock, water ? is there one Formula to rule them all? or do you...
  21. S

    Finding the frequency of a string based on Mass and Tension

    I saw the following problem in a test I was reviewing: I don't understand how they got their answer. I used the formula: ƒ=sqrt(T / u) / 2L where f is the frequency of the string, T is the tension, u is the linear mass density, and L is the length of the string. I got: T = mg = 50 * 9.8 = 490N...
  22. J

    Can Resistance Determine the Torque in a Solenoid Pendulum System?

    The flux enclosed by the loop consisting of the solenoid, wires and conducting rod at an angle θ is Φ = blBsinθ, then using small angle approximations and differentiating the induced emf can be found. I know that there must be some torque opposing the motion but am unsure how to proceed.
  23. D

    I Time & Gravity in Rotating Faster Than Light?

    If a person was rotating on a verticle axis from head to toe like the Earth or quasar. If nothing can go faster than light, from the person's perspective looking at the stars traveling across the night sky, if you increase the rotation of the earth, stars further than a certain critical distance...
  24. E

    Effect of temperature on vibrational frequency of a violin string

    Variables: Dependent: Vibrational frequency of violin string (Measured using mobile tuning app) Independent: Temperature in which string is plucked (Measured using infrared thermometer) Controlled: Violin String, Tension of violin string, Length of violin string, Method of plucking...
  25. Moondog

    Fog Droplet Size as a function of Ultrasound Frequency

    I need to know how to predict particle size of a water driplet produced by a given ultrasonic frequency? For example, an ultrasonic fogger will create ~5 micron water driplets at a frequency of 1.75 MHz. I do know that the higher the frequency the smaller the driplet diameter. How is this...
  26. mishima

    Finding Piezoelectric Crystal Frequency for Coherer experiment?

    Hi there, I've been fascinated by using simple coherers to pick up the electromagnetic signal from a spark (in imitation of early radio experiments, for high school education). I am using a push button ignitor (piezoelectric crystal) attached to a simple dipole antenna for the transmitter. When...
  27. Tobias Holm

    Find frequency such that two components have same average power

    (This is my first time posting here, sorry in advance for any difficulties. ) All componenets of same type has same magnitude, so e.g. the two resistors both have $R$ resistance. Given the difficulty of the previous exercises, I believe I'm over complicating the problem. However, here is what...
  28. zb23

    A Can a Solid Vibrate at Debye Max Frequency?

    Can a solid vibrate with only one frequency-Debye maximal frequency?
  29. B

    B Is the highest frequency possible the inverse of Planck time?

    Is the highest frequency possible the inverse of Planck time? Separate or connected question, what's the highest frequency achievable practically today?
  30. PainterGuy

    Signals with the same frequency spectrums but different power levels

    Hi, I understand that if there are two signals whose spectrums consist of different set of frequencies, they can be separated using a filter such as bandpass filter on the receiver end. Is it possible to separate two signals who frequency spectrums are the same but power levels are different?
  31. L

    At what frequency can Planck's law be used to determine the temperature?

    Hi, I am not quite sure if I have calculated the homework correctly :-) I proceeded in such a way that I first calculated from which frequency the two terms are equal, and thus the equation results in zero. Then I figured a relative accuracy of 10% equals a relative error of 90%. So I...
  32. P

    I What is the role of frequency in music?

    Setting aside pure sine waves, and looking instead at real-world sound, such as music, I wonder what "frequency" is? Fourier's Theorem seems to be aimed specifically at PERIODIC waveforms, but music (as just one example of real-world sound) is not periodic, as far as I can see. So it is not...
  33. C

    Resultant Frequency and Wavelength of Interfering Sound Waves

    ##-w1## and ##-w2## are to shift the cosine graph to the right, and ##\frac{2pi}{\lambda}## is to stretch the graph. But I can't seem to draw an appropriate ##y1+y2## graph (quite irregular) and I struggle to find the resultant frequency and wavelength. Also, why is there angular frequency in a...
  34. P

    LTSpice functionalities regarding its Frequency Domain Analysis

    The time domain analysis is easier to plot compared to analyzing the frequency with respect to the phase. But, LTSpice makes it look really easy. So, for a small signal AC analysis, LTSpice does use a AC voltage source for its frequency domain analysis function. This must be a really convenient...
  35. S

    Amplitude of standing wave for higher frequency

    I understand the part where there will be more nodes produced because number of wave produced will increase (let say from half wave to one wave). But I don't understand the part where the amplitude will be less. How can number of nodes (or frequency) affect the amplitude of standing wave...
  36. A

    Understanding CPU Frequency Waveforms and Dead Time in Modern Processors

    There was a thread recently in another subforums where a user talked about creating "square waves" at Ghz frequencies. It was said there that at that frequency range one cannot have a square wave as the inductance "rounds off" the edges making the waveform sine like. I am wondering then how...
  37. MisterH

    A Minimum sample length to estimate the frequency of a sinusoid

    Given a discretely sampled horizontal sinusoid of length p, and unknown amplitude, what is the minimal number of consecutive points on a window that is required to correctly estimate its total length, starting at any random point on the wave? Initially I would think it would be either p (full...
  38. Narayanan KR

    Resonant Frequency for a Coil-Only Antenna

  39. A

    Klystron beam current, drive frequency, LHC CW example

    First of all I want to ask , do the LHC power klystrons work always in CW or are their frequency shifted to correct for timing of the bunches in the LHC tubes in case something isn't aligned or doesn't that ever happen? Also how do they drive the klystrons at LHC or other CW operation from an...
  40. S

    Adding two sinusoidal waves of same frequency but out of phase

    Asin(wt)}+Bsin(wt+a) Asin(wt) +B sin(wt)cos(a) +Bcos(wt)sin(a) Asin(wt) + ksin(wt) + Lcos( wt) (A+K) sin(wt) + Lcos(wt) Fsin(wt) + Lcos(wt)
  41. Haorong Wu

    I Understanding Frequency in Rindler Coordinates for a Scalar Massless Field

    I consider a scalar massless field obeying the Klein-Gordon equation ##\Box \psi=0 ##. First, in Minkowski spacetime, a solution of the equation is $$ u_{\mathbf k}(x^\mu)=((2\pi)^3 2 \omega)^{-1/2} e^{ik_\mu x^\mu}$$ where ##\mathbf k=(\omega, \vec k)##. So this mode has a frequency of...
  42. Peter J Carroll

    I Quantum spin, wavelength and frequency

    Greetings, I'm new here, I have an interest in the nature of reality, and a question. Does the quantum spin of a particle (its intrinsic angular momentum) have anything to do with its wavelength and frequency? One of the experts on Quora said no, and I cannot find anything about it on the web...
  43. person123

    I Water Waves Over Obstacles: Higher Frequencies Grow, Not Decay

    In general, it seems that higher frequencies of a wave dissipate more than lower frequencies. For sound waves, it explains why you can hear lower pitches from farther away. For a vibrating string or plate, the higher frequencies also dissipate first, with the fundamental fading last. For water...
  44. I

    Cutoff frequency for this RLC circuit

    How would i find the cut of frequency of this RLC circuit .I have used LTspice to find it but what is the equation for finding it
  45. S

    Minimum Frequency of FM Data / Catastrophic Error Scenario?

    Ever since I learned about FM something's been bugging me, which is that the PLL error correction acts on the encoded data, seeming to leave open the possibility of the shape of the data itself interfering with the PLL's interpretation of what the carrier frequency is. It seems dangerous to mix...
  46. T

    Engineering Understanding Resonance in AC Circuits

    Here's my attempt at a solution.
  47. S

    Finding frequency of microwaves

    I thought 14 mm, 86 mm, 156 mm, 225 mm and 293 mm are the position where constructive interference happens 14 mm is the position of 1st maxima, 86 mm is the position of 2nd maxima and etc (measured from a certain position of center maxima) But when I used that numbers to calculate the fringe...
  48. I

    Engineering Frequency Response Between 100Hz and 100kHz

    So am trying to find the Frequency response of a RC LPF between frequencies 100Hz-100kHz ,but i don't know what formula to use .
  49. D

    I Is there a way to calculate the frequency of an electron wave?

    According to de Broglie, the wavelength of an electron wave is L=h/p. Is there a way to calculate the frequency of such a wave? Thank you!
  50. B

    Trouble with Plasma Frequency Calculation

    This would appear to be a straightforward algebra problem, but it just doesn't pass the smell test for me. The issue might be with the number of electrons per cubic meter, as that was calculated in a previous problem, so let me know if that number seems wrong. My plasma frequency (##\nu##) not...
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