What is Frequency: Definition and 1000 Discussions

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. harini07

    A question about wave motion and beat frequency

    Homework Statement 3 tuning forks of frequencies 200, 203, 207 Hz are sounded together.find out the beat frequency. Homework Equations Beat frequency= n1-n2 (n=frequency). The Attempt at a Solution I know that beat frequency is the difference in the frequencies of two superposing notes. But...
  2. T

    How does one compute frequency bandwidth based on FWHM

    In the following text the authors state: "The full width at half maximum (FWHM) we measure is about 2 km/s" and this is in the local standard of rest (LSR), ##v_{LSR}##. I have seen basic doppler shift equations to convert from these velocities to frequency (shown below in link). Although if I...
  3. Dante Meira

    B Does "wave–particle duality" exist in low frequency waves?

    Hello, I'm new to the forum, and Physics is not my area of study, but I have a doubt that I couldn't find a satisfactory answer on Google, so I created this account in this forum just to ask this, because I'm really curious to know the answer to this doubt. Does "wave–particle duality" exist in...
  4. B

    Gun sound -- frequency analysis

    Small caliber guns have higher magnitude at higher frequencies and larger caliber guns have higher magnitude at lower frequencies. is this true ? because I am not see this in my test: that is the fft of a 9MM gun, As one can see there are low magnitudes at low frequencies and higher...
  5. B

    Sound wave -- positive and negative frequency?

    does ever sound wave have a positive and negative frequency?
  6. T

    B Determining the transition frequency

    I was reading through a paper on MASERs, and perhaps it is obvious, but I am missing how authors determined what type of MASER it is. For example, the observed signal itself has a period of days and the bandwidth is on the order of ##10^{-5}## Hz yet the frequency of the transition responsible...
  7. S

    Frequencies -- what is the average frequency for the human body?

    Hi all, Would anyone be able to let me know what the average frequency is for the human body? Also, what is the average frequency of a home? What would be considered abnormal? According to the Ofcom UK Frequency Allocation Table it notes different frequency uses e.g. a frequency of 1,600...
  8. freakywarlock

    RC Oscillator Circuit Adjusting Frequency

    Hi, I am working on RC OScillator Circuit, but i had problems with adjusting frequency. I can adjust frequency but it effects amplitude too (amplitude is changing while adjusting frequency), how can i separate these two variables ? I mean, when I am adjusting frequency, I want to amplitude...
  9. Luke Frederiks

    Calculating frequencies with the Doppler Effect

    Homework Statement A train moves at a constant speed of v = 25.0 m/s toward the intersection shown in Figure P13.71b. A car is stopped near the crossing, 30.0 m from the tracks. The train’s horn emits a frequency of 500 Hz when the train is 40.0 m from the intersection. (a) What is the...
  10. A

    What Is the Correct Water Level for the Third Resonance in a Closed-Open Tube?

    Homework Statement A vibrating tuning fork of frequency 512 Hz is held over a water column with one end closed and the other open. As the water level is allowed to fall, a loud sound (resonance) is heard at specific water levels. Assume you start with the tube full of water, and begin steadily...
  11. A

    Calculating Ambulance Frequency Change: -113 Hz

    Homework Statement : An ambulance has a siren of frequency 880 Hz. You are sitting at a stop light as the ambulance passes you, traveling at a constant 22 m/s. If the speed of sound is 343 m/s, what is the change in the frequency that you hear as the ambulance passes you? A -53 Hz B...
  12. A

    Fundamental frequency of a wire wheel spoke

    Homework Statement The spoke of a wire wheel is 9.5 cm long, 3.5 mm in diameter, and under tension of 2100 N. The wire is made of steel of density 7860 kg/m3. When struck with a metal tool at its center, the spoke rings at its fundamental frequency. What is that frequency? Homework Equations...
  13. A

    Waves: fundamental frequency of taut cable

    1. Homework Statement The wire cable supporting the mast of a sailboat has a length of 12 m and a linear mass density of 350 g/m. When pushed sideways at its midpoint with a force of 160 N, the cable deflects by 9.5 cm. What is the frequency of the fundamental mode of vibrations on this...
  14. T

    Algorithm for dB vs time graph for one frequency from FFT?

    I'm doing a physics experiment for school, for which I am measuring the reverb time for specific frequencies in a room. What I did was record a 1000 Hz sound, and some time after it, and looked at its FFT on Audacity to see the intensity of just 1000 Hz at a given time. Manually, I can do this...
  15. I

    Determining the Correct Radio Frequency

    I am building a project where an object will be fitted with an RF transceiver and where it will face wooden walls as obstacles, with constant thickness "t". I am trying to look for an equation that would give the appropriate radio frequency that I would need to generate to have a radio wave...
  16. 1

    Question about frequency of light

    I flicker an LED on and off at a rate on the order of hundreds of kHz. The light, even though it is sent in pulses, still has its own frequency, correct? The frequency at which I turn the light on and off is not related to the frequency of the photons. Is this correct?
  17. justtryingtopass

    If R^2= L/C, show the total power is independent of frequency

    Homework Statement You have a circuit supplied with AC voltage, it has 2 parallel branches, 1 with R and L, the other with R and C. a) If (frequency) w^2 = 1/LC, prove that the power in each branch is equal. b) If R^2 = L/C, show that the power is the circuit is independent of frequency...
  18. G

    Intensity of EM wave independent of frequency?

    Hi. I'm a bit puzzled that the classical formula for the intensity of a monochromatic, linear EM wave $$I=\frac{1}{2}\cdot c\cdot \varepsilon_0\cdot E_0 ^2$$ seems to be independent of frequency whereas I find for the energy of a mechanical wave (e.g. on a string with total mass ##M##)...
  19. Passionate Eng

    Power & Frequency: Which Delivers More?

    If I have tow sinusoidal voltage sources, one with 50Hz frequency and the other with 60Hz. which one of them will deliver more power if connected to 1 ohm resistor?
  20. B

    Do I need a feedback card to acquire motor RPM from a VFD?

    The VFD I plan on using; DURApulse GS3 series AC drive: https://www.automationdirect.com/static/specs/gs3drives.pdf Model: GS3-22P0 The feedback card accessory for the VFD: https://www.automationdirect.com/static/specs/gs3fb.pdf Hi everyone, I would like to know if I need this feedback card to...
  21. NaukowiecGirl

    Phone Frequency Range: Can Smartphones Emit Below 15Hz?

    Hello guys! I have become a little curious, but what is the sound frequency range of which a phone can emit (from a speaker)? Can a smartphone, like a Samsung Galaxy, emit anything below 15Hz? My main concern is that I hope my phone can emit 7.83Hz but I am a little unsure if my phone is able...
  22. B

    Synchronous Sources and Interference

    Hi, What is the scientific definition of "synchronous sources" when we talk about the conditions of interference? Thank you.
  23. C

    Engineering Parallel Resonant Circuit Frequency

    Homework Statement Homework EquationsThe Attempt at a Solution I'm not exactly sure why my formula isn't working here. The correct answer given to us is 2.25kHZ.
  24. patrykh18

    Calculate the frequency of microwave

    Homework Statement Two single frequency coherent microwave beams are directed from the same point towards a concave mirror. One beam is incident parallel to the principal axis of the mirror, 0.06m from the axis. The other beam passes through the focal point before striking the mirror. The...
  25. Vanessa Avila

    Simple Harmonic Motion Given Amplitude and Frequency

    Homework Statement A cheerleader waves her pom-pom in SHM with an amplitude of 17.3 cm and a frequency of 0.830 Hz . Find the maximum magnitude of the velocity.Homework Equations v = -w Asin(ωt+Φ) = -wx or Conservation of Energy: 1/2kx2 + 1/2mv2 = 1/2kA2 The Attempt at a Solution I tried v =...
  26. B

    Is this Variable frequency drive compatible with this motor?

    My senior design adviser told me that the VFD must be the same brand as the motor that is being used, I'm not sure I believe this. I plan on using a GS1 series AC drive, here is a link; https://www.automationdirect.com/adc/Overview/Catalog/Drives/GS1_(120_-z-_230_VAC_V-z-Hz_Control) Here is a...
  27. B

    Understanding N-Stages of FFT & DFT Formula for Frequency Domain

    1) How many stages are in N numbers for a FFT? I know N=8 has 3 stages and N=4 has 2 stages ? 2) The DFT formula converts a signal from the time domain into the frequency domain. Is this done by comparing x[n] against signals known as sinusoidal basis functions? are e-j2 pi kn/N sinusoidal...
  28. D

    Fatigue analysis in the frequency domain

    Assuming that a TLP platform is examined and the wave forces acting on the tendons of the mooring lines are presented in RAOs (as a function of wave frequency). Using Jonswap spectra for North sea (i.e peakness factor equal to 3.3) we can obtain Hs (significant wave height); Tp (peak period) and...
  29. nfcfox

    Frequency of a mass bobbing up and down in water

    Homework Statement This was a test question I had today but basically, initially the mass is at rest as the buoyant force opposes the force of gravity. Then we push it down X meters and let it go. This can be described by SHM. We are also given the density of water, a cross sectional area of...
  30. cnh1995

    Automatic Load Frequency Control in a power system

    I am studying ALFC and I have a few questions about it. Consider the flyball governor in this system. It senses the changes in speed of the turbine. If load is increased, the balls will slow down and will move inwards, moving point B upwards. Now, this will open some additional valves to allow...
  31. 8

    Engineering Circuit analyse -- LR circuit frequency response

    Homework Statement Find X [/B] Homework Equations V1(t)=8cos(12000t) V0(t)=Xcos(12000t+θ) The Attempt at a Solution [/B] I've tried quiet a lot actually, but all in vain. Seems like I am either misunderstanding something, or i am just too tired to think at the moment. Either way, I am...
  32. Efast

    Waves: Find mass of an object given L, Frequency & Density

    Homework Statement An oscillator is attached to one end of a horizontal string. The other end passes over a frictionless pulley and is held taught by a mass m. The distance between the oscillator and the pulley is 1.2m. The string has a linear mass density of 1.6g/m and the frequency of the...
  33. J

    Amplitude and Frequency: Exploring the Relationship and Impact on Sound Waves

    Hello all, First of all, let me say that I am aware that a higher amplitude doesn't translate into a higher frequency. However, my understanding of how for example a string vibrates makes me draw other conclusions. From what I understand, hitting a string with a particular force makes the...
  34. S

    B Moving to a higher harmonic in a standing wave

    Imagine that you have plucked a string and it is vibrating as a standing wave at its fundamental tone (frequency f1). You leave it there and later on come back with the intention of bringing it up to the second tone (frequency f2). What should you do? It seems obvious: apply a stimulous...
  35. B

    Why sound produced by rapids varies in pitch based on height

    The other day I was at a river listening to some rapids. The sound produced by the rapids appeared to vary in pitch depending on how high up I was (squatting down to the ground and standing up produced about a fifth in the variation of the pitch); and I can't think why it should be? Many Thanks
  36. B

    Why Didn't Glass Break When Tone at 775.195 Hz Played?

    I hit a glass and ran the sound though a FFT and I found the tone is 775.195 Hz. I then tried to play the tone out of my computer and this glass did not break. This is the equation I am using: Amplitude * Math.Sin(Math.PI * Frequency * n2 / 44100D) I set the Amplitude to 3 and the Frequency to...
  37. DoobleD

    Light intensity independant of frequency and E = hf

    Isn't it weird that light intensity (which is time average of Poynting vector) doesn't depend of the light frequency, while the energy of a photon does ? From E = hf it seeems that frequency would have an impact of light energy flux (even time averaged). But intensity, which is a (time...
  38. G

    MHB Number Theory for Electronic Signal Frequency Synthesis

    I am new to this forum. I am an electrical engineer designing frequency synthesizers for electronic test and measurement equipment. I have a design problem and I think that number theory could help me solve it. I'm not a mathematician, so I will state the problem the best I can. Definitions...
  39. terryds

    Frequency of Beat in Transverse Wave

    By addition of transverse wave, I can get a beat. ## y_1 = A\ \sin (\omega_1 t + kx)\\ y_2 = A\ \sin(\omega_2 t + kx)\\ --------------------------------- + \\ y_1 + y_2 = 2A\ \cos(\frac{\omega_1-\omega_2}{2} \ t) \sin(\frac{\omega_1+\omega_2}{2} \ t + kx)## So, I get new amplitude as a function...
  40. blue.flake

    What is the period of the loaded tuning fork?

    Two identical tuning forks vibrate at 256 Hz. One of them is then loaded with a drop of wax, after which 6 beats/s are heard. The period of the loaded tuning fork is? So, as the uploaded pictures shows, I did solve the problem, but I'm not sure why the f1 frequency is bigger than f2. I mean how...
  41. Meerio

    I Frequency of GW Arm Length Change: Properties & Detailed Explanation

    What properties have to do with the frequency at which the lengths change of the arm? Also does anybody have a body paper or webpage which explains the properties at a detailed level?
  42. Monoxdifly

    MHB [ASK] Are the Frequency and the Score Switched?

    Pay attention to the table below. \begin{array}{|c|c|c|c|c|c|}\hline Frequency & 5 & 6 & 7 & 8 & 9 \\ \hline Score & 6 & 6 & 10 & 15 & 5\\ \hline \end{array} The amount of students who get above average are... A. 9 students B. 17 students C. 18 students D. 26 students I got the average as...
  43. I

    Difference between rate and frequency?

    Is rate of collision and frequency of collision the same ? In what ways are they different ?
  44. B

    Natural Frequency & damping coefficient from transfer function

    Homework Statement Here is the transfer function of a buck converter I derived: What I need to do next is obtain equations for w0 and ζ. I know how to do this for equations that follow the general form: But in this case I just can't figure out exactly how to do it. How do I find a...
  45. F

    The reciprocal relationship between frequency and period

    I was asked by a friend to explain why the frequency, ##f## and period, ##T## of a wave. The initial explanation I gave to them was as follows: Heuristically, the period of a wave is defined as ##T=\frac{\text{number of units time}}{\text{cycle}}##, and its frequency as ##f=\frac{\text{number...
  46. Giannakoulis

    Problem in a circular motion (find the max Frequency)

    In the figure below we put a small coin on a disc, which rotates at constant frequency f, at a distance D=0.2m by the disc rotation axis. If the coefficient of friction is μ=0.5, then what is is the maximum frequency that can have the disc so that the currency does not slip? g=10 m/sec^2 Anyone...
  47. D

    What is the Resonant Frequency of a 2-Year Old's Outer Ear?

    Homework Statement A 2-year old child has an outer ear length of approximately 1.7 cm (compared to 2.5 cmfor an adult). Find the resonant frequency of the outer ear of the average 2 year old b.Draw a diagram of the natural harmonic for the child’s ear. Homework Equations f=v/waveleng where...
  48. Marcin H

    Engineering How to Simplify a Frequency Response Circuit for Impedance Calculation?

    Homework Statement Homework Equations V=IR H(w) = Y/F = Impedance of circuit The Attempt at a Solution I wanted to simplify this circuit before I find any impedance, but I am not sure if I did my source transformation correctly. Can i combine the f(t) current source with the 1ohm in...
  49. Clara Chung

    What actually is threshold frequency?

    For example a metal atom have 3 electrons which occupies 2 energy level. Is the threshold frequency = the energy needed to bring an electron in E2 to E(infinity) / h?
  50. ramzerimar

    Where does natural frequency comes from?

    I know everything has a natural frequency that is a intrinsic property to the body in question. For example, a string vibrating has the largest amplitudes when it's vibrating near it's natural frequency, and the same thing happens with other things too (like the Tacoma Bridge). Natural...
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