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. S

    Understanding a sound spectrum analyzer output

    Hi, I am just trying to understand the output of a sound spectrum analyzer. There are three dimensions 1) Time 2) Frequency 3) Volume (db) I am confused about few things here: 1) How should I perceive the volume dimension here? 2) Why are the db values negative here and w.r.t what reference...
  2. B

    Resonance frequency increasing with mass?

    For a spring and mass system, I've learned the resonance frequency of a system increases with decrease in mass. Not sure if this case is also related but when I attach a coin sized metal onto a piezoelectric material of a smaller size, the resonance frequency range actually goes up (from...
  3. Y

    Integration in Frequency Domain

    How to integrate $$\int_{-0.5}^{0.5} {\bigg({\frac{1}{4-2e^{-j2{\pi}f}}}\bigg)}^2 df$$
  4. B

    What Is the Correct Period and Frequency for an Electron in a Magnetic Field?

    Homework Statement Find the period and frequency of the motion of an electron of kinetic energy, E, 34 KeV as is moves in a circular orbit perpendicular to a magnetic field, B, of 0.270 T.Homework Equations For speed, v: For charge, q: For mass, m: For radius, R: For frequency, f...
  5. B

    Question about Nyquist frequency and noise

    Homework Statement A time series is sampled at 250 Hz. What is the sampling interval and Nyquist frequency of the original signal, before digitising was contaminated with noise at about 300 Hz. At what frequency would this noise appear in the spectrum of the digitised sequence ? Repeat the...
  6. goonking

    Fundamental frequency of oscillation in 2 ropes

    Homework Statement Homework EquationsThe Attempt at a Solution if the material are the same in both strings, then the density should be the same. v = sqrt (tension/μ) tension in the first string should be 30 kg x 9.8 m/s^2 = 294 N next, v = λƒ and string#2 needs to have twice the...
  7. goonking

    What is the length of a vibrating metal wire at its third harmonic frequency?

    Homework Statement A metal wire is vibrating at its third-harmonic frequency. 0.32 m from one end, the amplitude is equal to one quarter the maximum amplitude. Find the length of the wire. Homework EquationsThe Attempt at a Solution I don't quite understand the question, it says 0.32m from one...
  8. goonking

    Frequency and Length: Solving for String Length

    Homework Statement Homework EquationsThe Attempt at a Solution for the first harmonic, the wavelength is twice the length of string. so 0.296m x 2 = 0.592m is the wavelength with the wavelength and frequency known, we solve for v in v = ƒλ v = 0.592m x 440 Hz = 260 m/s then to solve for...
  9. Chrono G. Xay

    Predicting Initial Length of String Needed Before Stretch

    I have put together an equation whose purpose is: With a desired 'magnitude of static friction' ( μ_s ), 'fundamental frequency' ( f ), and 'tension' ( T ), initial conditions such as 'string breakover angle' ( Θ_0 ), 'nut-tuner distance' ( L_{h,0} ), and 'string diameter' ( d ), and...
  10. M

    Why does vibration always cause air to vibrate with it?

    When an object vibrates next to another object with the same resonant frequency it causes it to vibrate with it. Why is it that when an object vibrates, it always causes the surrounding air to vibrate with it?
  11. Chrono G. Xay

    Tension (and Frequency) with Change in Temperature

    At one point I had been trying to construct an equation which would calculate the tension on a tuned string with a change in temperature (and therefore the fundamental frequency), but found my calculations were wrong. By extension, the purpose of the project was to be able to calculate what...
  12. M

    Natural Frequency: Find Equation of Motion

    Homework Statement Find the natural frequency Homework Equations On picture The Attempt at a Solution Just need help with the equation of motion.
  13. J

    How do significant digits work in physics calculations?

    A guitar string vibrates 750 times in 3.00s. Calculate period and Frequency. I am in grade 11 and it is my first week in physics 11 so I'm new at this! My question is on how the significant digits work. I don't know where I should leave my answer..Here is my attempt: Period: 3.00/ 750 =...
  14. L

    Adding waves of the same frequency but different phases

    Homework Statement how do you add two waves with the same frequency but different phases? E1 = 7*sin(omega*t + 70degrees) E2 = 13*sin*(omega*t + 65degrees)[/B]Homework Equations Er = E1 + E2[/B]The Attempt at a Solution I know how to add waves that only have one phase, i.e. E1 =...
  15. Y

    Frequency spectrum in Doppler effect

    Homework Statement I have been investigating the Doppler effect in a circular motion with a stationary source and moving observer (however the main aim is to determine the speed of sound in the end). Using Vernier software - Logger Pro - I have obtained two graphs of the sound pressure against...
  16. S

    What is the frequency of the sum of several sine waves?

    I am given three sine waves with individual frequency being 10 Hz, 50 Hz, and 100 Hz. What is the frequency of the following : y(t) = sin(2π10t) + sin(2π50t) + sin(2π100t) Is it simply 100, the LCM of all the sin waves? If not, How to calculate the frequency of y(t) ?
  17. Y

    Derivation of cutoff frequency for RC circuit?

    How is it derived? The cutoff frequency is Fc = 1/2piRC. R = resistance, C = capacitance. I read somewhere it has to do with Laplace Transforms, but I'm not sure where to go from here. It kind of irks me to just accept this equation without some proof. Thanks!
  18. K

    Frequency of sound involving bamboo flutes

    Dear all, I have been attempting to create a range of bamboo flutes with different lengths for my physics practical. I am trying to calculate the theoretical frequency that should be produced by a particular length of flute, but all my flutes have different diamaters and I am searching for an...
  19. mishima

    Mirrored pattern in antenna dB vs frequency, explanation?

    Hi, my high school astronomy class designs/builds antennas to detect VLF radio for solar flare detection. Recently, and regardless of their design, we get a strange "mirrored" shape to the dB vs frequency plot. The shape of the graph before roughly mid-band is exactly mirrored about the...
  20. K

    What is a frequency domain and s domain?

    What is a frequency domain and how can we understand the same in practical world? How is it related to complex plain sight domain?
  21. S

    Is Frequency Quantized in Quantum Mechanics?

    As to E=hf I understand that a energy can be arbitrary in order of proportional packages to given frequency. But is there any equation in quantum mechanics which imply a freq to be quantized? Thanks a lot!
  22. Q

    How to work out expected frequency from normal distribution

    How is the expected frequency column worked out for each interval of trains? 2) My attempt Take the first interval, 60 - 62, I thought about doing this: (62 - mean) / standard deviation (62 - 67.45) / 2.92 = - 1.866 using Z score < - 1.886, from the normal distribution table, I get: 1 -...
  23. S

    Phonon frequency spectrum distribution

    hello every one , I want to know how we get phonon frequency spectrum theoretically by using three modes and dispersion relation, can anyone explain it. for example it is phonon energy correspond to density of state how it is obtain?
  24. M

    Calculate the angular frequency w using the Euler equations

    Homework Statement Consider the Earth as a rigid body with moment of inertia I1, I2 and I3. The Earth is symmetric around the z-axis (I1 = I2). Calculate the angular frequency w using the euler equations Homework EquationsThe Attempt at a Solution
  25. Gary Trinder

    Audio Crossover Frequency Equation....

    Can anyone verify or correct this equation to work out the crossover frequencies of a three tier sound system please? I never was the best in my physics classes... (Please find attached "Crossover Freq.dpf") And thank you in advance for your time. Sorry about the way i have had to write...
  26. B

    What affects the intensity of different coloured lights?

    Okay, so I have completed a practical where I used a light box and then placed different coloured plastics in front of the light and measured the light intensity of each colour. From the results I found that yellow, orange and violet had the highest intensities, with red and green having the...
  27. Spacexplorer

    Understanding How Dampers and Springs Work in Car Suspension Systems

    Hi guys. It could be an easy question but I started at the deepest. I wonder how it works like a car suspension system. How does damper work with spring? What is the difference between forced-nonforced systems? Why do we calculate frequency of spring? What does it provide us? What is the point...
  28. S

    How is the frequency unchanged in elastic wave scattering with a crystal?

    it makes sense that with an inelastic scattering process, a wave approaches a crystal, and then some energy is imparted to the phonons, so that the outgoing wave has a different frequency from the incoming wave. However, with an elastic scattering process, the frequency is unchanged-- how does...
  29. H

    How to set the frequency of a switch in NI Multisim software

    I am a new user of Multisim and I am trying to make a buck converter. In other softwares, such as pspice I was able to control the switching frequency by editing properties but in Multisim, most of the switches are user interactive. I want to set frequency of 50 Hz in a switch. Kindly help me...
  30. C

    Can someone zero in on one person's frequency?

    I'm new, so first let me just apologize if I ask a stupid question! I recently had a bad breakup with my boyfriend, and he pretty much told me I was crazy and he was going to make sure I got some help. I've been experiencing some strange things in my life since he said that, and my family now...
  31. K

    Relating pavement roughness in frequency to displacement

    Hi all, I'm attempting to optimise a suspension system's spring and damping rate via vibrational analysis. Working in the frequency domain, I have calculated the input-output relationship as a ratio (i.e. ground to body, x/q2 in the attachment) and the mean square acceleration response based on...
  32. TomW17

    Natural frequency of a simple harmonic system

    Homework Statement Derive the natural frequency f_n of the system composed of two homogeneous circular cylinders, each of mass M, and the connecting link \text{AB} of mass m. Assume small oscillations. Homework Equations The sum of the kinetic + potential energies in an isolated system...
  33. Luke Cohen

    If the angular frequency of the generator exceeds 1/sqrt(LC)

    Homework Statement If the angular frequency of the generator exceeds 1/sqrt(LC), the average energy stored in the inductor is greater than the average energy stored in the capacitor. True of False? Can someone explain to me the derivation of this answer? Homework EquationsThe Attempt at a...
  34. K

    What is the stretch of the spring?

    Homework Statement A spring scale hung from the ceiling stretches by 6.3 cm when a 1.2 kg mass is hung from it. The 1.2 kg mass is removed and replaced with a 1.4 kg mass. What is the stretch of the spring? F=mg U (spring force) = 1/2kx^2 Homework Equations The units of cm need to be...
  35. S

    Wave frequency and propagation attenuation

    In my memory, the wave frequency will decrease because the attenuation in wave propagation, is that true? Can someone please give me some links to prove or disprove it? thanks
  36. D

    Compute damping as a function of frequency

    Hi everyone, I'm french, so sorry for my bad english. I have a problem to compute the damping as a function of frequency. In fact, I plot the transfer function between the input (which is a force applied bu a hammer) and the output (which is an acceleration). Therefore, I can analyse the mode...
  37. M

    High Frequency that can cause g-sensor damage

    Hello All, Anyone can help, but first allow me to give you some background, I have a project this project is to measure the frequency of the PCB depaneling machine that might damage the sensetive component which is the gyro-sensor. The sensor will damage if the frequency is above 75kHz or 100...
  38. I

    Find the frequency of the oscillation of a horizontal beam.

    Homework Statement A uniform meter stick of mass M is pivoted on a hinge at one end and held horizontal by a spring with spring constant k attached at the other end. If the stick oscillates up and down slightly, what is its frequency? [Hint: Write a torque equation about the hinge.] The length...
  39. KaseyKC

    Relationship between wavelength and frequency in a medium

    Homework Statement Write down the relationship between the linear frequency and the wavelength of a light wave when the wave is propagating in a medium of refractive index, n.[/B]Homework Equations wavelength x linear frequency = speed of light speed of light = refractive index x speed of...
  40. Merttt

    What is the General Frequency of Unsteady Pressure in a 2.2 mm Pipe?

    Hello everyone; What is the general frequency of unsteady pressure when we measure by the using transducer and diameter of pipe inside can be 2.2 mm? Can someone provide a proff also ? I mean scientific paper. Thank you
  41. E

    Phase shift in frequency domain

    Hello, I'using Matlab to simulate phase shift in frequency domain (FD). I have got real and imaginary parts of the signal after FFT. I'd like to use phase shift in FD. This works: Y=fft(y); YY=Y.exp(-i*2*pi*nk/N*samples_delay); result=ifft(YY); But in my DSP I can't use the formula above and...
  42. V

    How Many Slits Are in the Stroboscope for Ripple Tank Waves?

    Homework Statement Say we are observing plane wave patterns on table. The depth of water is the same everywhere in ripple tank. The frequency of waves is 12 Hz and wave length is L (lamda). We see the wave pattern as stationer while looking at wave pattern through the slots of stroboscope which...
  43. I

    Transformers and iron cores and frequency

    As far as i understand the thing that matter in all of the process of mutual inductance is the rate of change of the current in the primary coil $$\frac{dI}{dt}$$ butting soft iron core will increase the density of the magnetic field inside the primary coil, but how this will effect...
  44. E

    Simulation low frequency ferrite core recieving antenna

    Hi everybody i want to simulate, low frequency ferrite core receiving antenna . but i can't find a good and complete software or method to do this. what is your suggestion or experience? thanks for your attention.
  45. dreens

    Frequency Components of a Lightning Strike

    Hi there, I recently attended a physics demonstration (Lightning show at Boston Museum of Science, my favorite exhibit obviously), where the educator argued that the reason she could safely sit in a Faraday Cage while lightning was striking said cage was the skin effect. As I understand it...
  46. A

    Varied frequency power supply for strobe light

    I'm looking to build a varied, high frequency power supply for a strobe light. Any suggestions on the best way to go about this? I would prefer to have it computer controlled so that I can change the frequency without manual input. Any pointers would be really appreciated! Thanks!
  47. ShayanJ

    How to know there is a frequency shift?

    This is a question that I've had for years but because astrophysics and cosmology are down in the list of my interests, I constantly forget and remember the question. My question is, how do we know there is shift(red or blue) in the spectrum of the light coming from a star? Because for...
  48. neilparker62

    Geo Coronal Absorption Frequency

    From this article on the monitoring of the solar Lyman Alpha emission line, a diagram (attached below) shows the 'mother of all absorption wavelength measurements': namely the geo coronal absorption of solar Lyman Alpha radiation at 1215.664 A or 121.5664 nm. Is this still the most accurate...
  49. desta41

    Vibrational frequency of electrons in atoms

    Below is a paragraph taken from the web site, physicsclassroom.com: 'It is often useful to think of these electrons as being attached to the atoms by springs. The electrons and their attached springs have a tendency to vibrate at specific frequencies. Similar to a tuning fork or even a musical...
  50. avito009

    Does loud voice mean high frequency?

    As I know: Velocity of sound = wavelength x frequency. If frequency increases wavelength decreases. So even if you shout loudly the velocity of sound won't change only that you will hear a louder voice. So does that mean that louder voice has higher frequency?
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