What is Frequencies: Definition and 411 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.

View More On Wikipedia.org
Recent contents Top users
  1. B

    Deduction of the equation of frequencies of a piano

    I'd like of know from where originated the funcion f(n) presented in this page (https://en.wikipedia.org/wiki/Piano_key_frequencies)!? Probably, f(n), is the solution of some differential equation and I'd like of understand how this diff equation was architected. If someone can answer this...
  2. saybrook1

    Solving for normal frequencies with a gravity term

    Homework Statement Hey guys, I have been making progress in classical mechanics but I'm having a tough time figuring out how to solve for the normal frequencies for this set of equations of motion: http://imgur.com/nQKPNsu In order to account for the mass gravity term here the book suggests...
  3. T

    Frequencies of the first three overtones in a string?

    Homework Statement A violin has an A string in tune at 440.0 Hz; as is the E string at 660.0 Hz. The tension force on each of the strings is 25.0 N. The linear density of the A string is 1.00 g/m. What are the frequency of the first three overtones for each string? Homework Equations f = v/ λ...
  4. A

    Minimum and Maximum Observed Frequencies?

    Homework Statement Let's say you want to find the minimum and maximum observed frequencies of light observed on Earth from the sun, when considering the Earth's motion around the sun. How would you go about doing this if you assume Earth takes time X to complete a revolution around radius R...
  5. TheExibo

    The correct way to calculate allelic frequencies?

    Homework Statement Out of a total of 43 people, 15 contain the genotype TT, 16 with Tt, and 12 with tt. Need to determine the allelic frequency of the recessive allele t. Homework Equations 1=p2+2pq+q2 1=p+q The Attempt at a Solution By counting up the individual alleles and divided by...
  6. J

    Frequencies of atoms/molecules

    It has been a long time since I have studied science. I have forgotten some of the basics. And in some cases, it seems that I have forgotten to ask my professors some questions. So I hope this community can help. I have a series of questions, all relating to "frequency" of atoms/molecules. 1...
  7. DeldotB

    High pass filter response at high frequencies

    Good day all, I have a question: I built a passive high pass filter in an experiment using a hand wound inductor (toriod) and a resistor. The filter worked great as a high pass at frequencys ranging from 100 Hz - 1,000,000 Hz (rolling off around 10,000 Hz). After creating a bode plot, I...
  8. Shackleford

    Relative Frequencies of Payment Methods for Purchases

    Homework Statement [/B] Relative frequencies of amount purchased and method of payment Cash Credit Debit $<20 .09 .03 .04 $20-$100 .05 .21 .18 >$100 .03 .23 .14(a) What...
  9. D

    Classifying standing waves and their frequencies

    Homework Statement 40-cm long string, with one end clamped and the other free to move transversely, is vibrating in its fundamental standing wave mode. If the wave speed is 320 cm/s, the frequency is[/B] A 16 Hz B 8 Hz C 32 Hz D 2 Hz E 4 Hz Homework...
  10. lonely_nucleus

    Do capacitors block unwanted ac frequencies in the wires?

    I have been studying capacitors and inductors recently and I have seen this video. I have a few questions about capacitors and inductors. Capacitors: 1.how do capacitors discharge? 2. What happens when you apply direct current through a capacitor? 3.Do capacitors only allow certain...
  11. E

    Spatial Frequencies of the Fourier Transform

    The Fourier Transform transforms a function of space into a function of frequency. Considering a function ##f\left(x, y\right)##, the Fourier Transform of such a function is ##\mathcal{F}\left\{f\left(x, y\right)\right\} = F\left(p, q\right)##, where ##p## and ##q## are the spatial frequencies...
  12. Tam Le

    Hearing which natural frequencies

    If you pluck a guitar or cello string, the string vibrates at its fundamental and harmonic frequencies. Suppose the 3rd harmonic has the greatest vibrational amplitude out of all the other rung-out natural frequencies. Do we still associate the pitch with the fundamental, or will the pitch now...
  13. curiousman

    Why are high frequencies bands chosen in satellite communication?

    Hi all, I'm an student of Physics so apologies if I'm just some silly questions here. The higher frequency bands typically give access to wider bandwidths (e.g wifi). Considering that higher frequencies bands (> 30 Ghz) are more susceptible to signal degradation due to ‘rain fade’...
  14. R

    Multiple Sources At Different Frequencies (Probability)

    Hi My prob theory is rusty and I am a little embarrassed I can't figure this one out - but: If we have two sources A and B that are producing an output at different frequencies - say A produces outputs every 100ms and B produces an output every 250ms .. Obviously even if they are perfectly...
  15. A

    Calculation of different natural frequencies of a material

    Hi, As far as I know, every material has different sets of natural frequencies associated with it. For example, A simple one dimensional oscillator with stiffness "k" and mass "m" has a formula for calculating its natural frequency = 1/2pie*squareroot(k/m). I was wondering if there are...
  16. H

    Principal frequencies of a Waveform

    Homework Statement Identify the principal frequencies in the current waveform Homework EquationsThe Attempt at a Solution From the excel file, I have identified 3 principle frequencies at 52Hz, 246Hz and 351Hz. Is this correct? What does the term principle frequency actually mean?
  17. mooncrater

    Pipes, resonating frequencies and yeah some gases

    Homework Statement A closed organ pipe resonates in its fundamental mode at a frequency of ##200Hz## in ##O_2## at a certain temperature. If the pipe contains 2 moles of ##O_2## and 3 moles of ##O_3## are now added to it, then what will be the fundamental frequency of same pipe at same...
  18. P

    Quantum fluctuations at radio frequencies

    Hi. I'd like to learn how to calculate the probability of a photon being emitted from a radio antenna where the energy per wavelength is below the threshold to emit photons. Let's assume the electrical thermal noise is insignificant. The antenna temperature could be sufficient low or the...
  19. Boccadoro

    The challenge of transmitting radio frequencies underwater.

    If both a transmitter and receiver antennae were submerged, and within a defined range and depth, what range might be available to a civilian operator? Are two divers able to communicate by radio? B
  20. J

    How to get specific frequency and time values for .wav file

    How to get specific frequency and time values for .wav file and export the values as .csv? Problem: I need to analyze this music .wav file, particularly for its frequency, amplitude, and pitch over specific intervals of time. Is there any easy to use software and steps I can take that can...
  21. B

    Medical Is there a way to measure light frequencies of brainwaves

    Is there a way to measure the light frequencies of brainwaves outside of the brain.
  22. T

    Natural Frequencies and Harmonics

    Homework Statement Basically, I was reading the following passage from a textbook, and I'm confused as to why they mention natural frequencies? Doesn't each harmonic have just one frequency that it oscillates at? From what I understand, the natural frequency is just the frequency an object...
  23. R

    Maximum and minimum values of a variable capacitor

    Homework Statement A parallel circuit like that in the figure forms the tuning circuit for an AM radio. If the inductor has a value of 8.6×10-6 H, what must be the maximum and minimum values of the variable capacitor if the radio receives frequencies from 590k Hz to 1670k Hz? a) Maximum C? b)...
  24. electronic engineer

    Sampling Frequencies: f1, f2, f3 with fs=1000Hz

    Homework Statement We have the following signal frequencies: f1=18 Hz, f2=510 Hz, f3=1100 Hz when using the sampling frequency fs=1000 Hz. how would these signals be like? my question is if I could use the same formula stated below for all the frequencies f1,f2,f3.. because the second and...
  25. G

    Fundamental frequencies of square wave and sine wave

    Homework Statement What are the fundamental frequencies for a 50 kHz square waveform of 50% duty cycle and a 25 kHz sinusoidal waveform, respectively? (The duty cycle of a square waveform is the ratio between the pulse duration and the pulse period.) Homework Equations My teacher then gave...
  26. Charles Stark

    Natural Oscillation Frequencies

    Homework Statement Over the years, buildings have been able to be built out of lighter and lighter materials. how has this affected the natural oscillation frequencies of buildings and the problems of resonance due to passing trucks, airplanes, or by wind and other natural sources of vibration...
  27. N

    Frequency Question -- 24 VAC, 60 Hz versus 24 VAC, 20 Hz

    Suppose that I have two sources: 1. 24 VAC, 60 Hz and 2. 24 VAC, 20 Hz Then I will use it to power into certain load (maybe we can assume a purely resistive load to simplify the question). What would be the effect of those sources to the load? How about the current flowing? I think (1) and (2)...
  28. G

    Structural Vibrations Analysis & Simulation

    Recently I created a structural vibrations simulation and would like to hear some feedback or suggestions.
  29. F

    Resonating frequencies of tubes

    Greetings, didn't know where to post this. To which category it fits, if even any. Anyway, I'm studying sound production and am doing a work on resonating frequencies of a certain tube. Please bare in mind I'm not a physician or in the studies of physics, just a musician trying to understand...
  30. M

    Minimum time window needed to capture frequencies

    I'm pretty sure there have to be some theorems out there, but I am probably not putting in the right search terms to be able to find them. Here's the problem: I have a signal uniquely composed of a finite summation of standing wave sinusoids (well there's some DC and other background, but let's...
  31. A

    Determining if a pipe is open or closed from given the resonant frequencies

    Homework Statement A pipe resonates at successive frequencies of 540 Hz, 450 Hz, and 350Hz. Is this an open or a closed pipe? Homework Equations -- The Attempt at a Solution My assumption is that because the harmonics of an open pipe are odd number multiples of the fundamental frequency (1f...
  32. T

    Violin frequencies and harmonics

    Homework Statement A violin has four strings that are 32 cm long and are typically tuned to concert G, D, A, and E (196 Hz, 294 Hz, 440 Hz, and 660 Hz). A)What is the wavelength of the fundamental mode of oscillation on the A string? Sketch the waveform. B)What is the wavelength of the sound...
  33. B

    Blocking ISM band frequencies

    The ISM band is a set of frequency bands from about 6 kHz to 246 GHz; see http://en.wikipedia.org/wiki/ISM_band#ISM_bands. Is there a design that will block all of these bands? A guess is in the attached file: each box is solid metal or wire mesh, and the boxes nest in a Matryoshka-doll fashion.
  34. O

    Components of standing wave between harmonic frequencies

    Hi, For a wave fixed at both ends, what is the behaviour of the original and refelcted wave between the harmonic frequencies? I understand how a standing wave is created by the superposition of a wave and it;s reflection at a boundary. I also understand that at the fundamental frequency of the...
  35. E

    RLC Circuit Frequencies Help

    Homework Statement In each of the four circuits shown, an AC input voltage, ##V_0 cos(\omega t)## is applied on the left and the output voltage is measured on the right. Treat the input frequency as a...
  36. PhysicsKid0123

    Natural vs normal vs resonant frequencies

    is there a difference between natural frequencies, normal frequencies, and resonant frequencies? Any subtle differences? I've seen them used at different times, and I've also seen at least two used in a single sentence implying some kind of difference. For example, "Natural Frequencies and...
  37. B

    MHB Fourier Transform to find sidebands with 2 different frequencies

    Hi Folks, I need to evaluate the following function f(t)=A[1+B \cos(\omega_1 t+ \phi)] \cos(\omega_2 t+ \phi) to find f(\omega) using the Fourier transform. Ie, the Fourier transform I use is f(\omega)=\displaystyle \frac{1}{\sqrt {2 \pi}} \int^{\infty}_{-\infty} f(t) (\cos \omega t+ j \sin...
  38. A

    At what angular frequencies is the amplitude half of its resonant value?

    Homework Statement A simple pendulum has a length of 1m. In free vibration the amplitude of its swings falls off by a factor of e in 50 swings. The pendulum is set into forced vibration by moving its point of suspension horizontally in SHM with an amplitude of 1 mm. a) Built Differential b)...
  39. Adriane

    Allele frequencies of the next generation

    Homework Statement Starting with 75 light-colored beans and 25 dark-colored beans, the 100 beans represent my gene pool. Light beans = F and dark beans = f. p = (total F alleles) / (total number of beans used) And now I'm stuck where it's asking me to "practice determining the initial allele...
  40. V

    Rational ratio of frequencies leads to isolating integral of motion

    Hello All, Padmanabhan's discussion of dynamics mentions that in general the two dimensional harmonic oscillator fills the surface of a two torus. He further notes that there will be an extra isolating integral of motion provided that the ratio of frequencies is a rational number. This last...
  41. C

    Calculating frequencies and velocity

    [Mentor's note - This thread was moved here from a non-homework forum, therefore it does not use the template.] Hi guys Need some help answering questions about frequencies and calculating velocity. I'm given two frequencies: 470Hz for an approaching object, 440Hz for when the object is moving...
  42. K

    Discrete fourier transform data of 2 different sampling frequencies

    Hi All, I have a problem I've been thinking about for a while, but I haven't come up with a really satisfactory solution: I want to do a discrete Fourier transform on data that has been sampled at 2 different sampling frequencies. I've attached a picture of what my data will look like...
  43. Salvador

    Transistor various frequencies

    Good day , Transistor characteristics tend to change under load and at various frequencies and teperatures etc, but when we have a simple linear class ab amplifier with two bjt output devices , I wonder how does a single transistor output various frequencies at once? I understand it's...
  44. S

    Oscillator driving frequencies

    I've attached a graph to this post. Why is it that the periodic external frequency applied never starts at 0 on graphs like these?
  45. M

    What's so special about resonant Frequencies?

    What's so special about resonant Frequencies ( or length of the pipe) in an pipe: As I understand it, if any two waves pass by each other in different directions, they will create a sort of standing wave with anti-nodes and nodes ( hence beats). They always show...
  46. DanielMB

    Is our Vision System sensitive to Wavelengths or Frequencies?

    Our Vision System should be sensitive to one specific term, they do not mean the same, one is related with geometry factors (wavelength) while the other is related with beating stimuli (pulse) The frequency of light (f) is constant from media to media, the same as it is in vacuum, wavelength...
  47. S

    Superposition of two waves with different frequencies

    Homework Statement Hi all! It's a superposition question: Two waves travel through dispersive medium, with different frequencies and wave number. P1(t)=Acos(k1x-w1t) P2(t)=Acos(k2x-w2t) Obtain the P(t)=P1(t)+P2(t) Homework...
  48. C

    Sound diffraction around obstacles; low and high frequencies

    Hi, I am posting here as I can't get a satisfactory answer from google. Could anyone explain to me why low frequency sounds diffract better than high frequnecy sounds around a corner (eg the wall of a building). I understand the idea of 'wave diffracts more when opening is around the same...
  49. A

    Waves, frequencies and tones

    I am a Swedish exchange student, it is the first time i am on this website and truthfully i am desperate. I need to know how to solve these 4 basic questions. Homework Statement 1. A feather is pulled out 4 cm if you hang 50 grams in it. If the spring is then loaded with a total of 150...
  50. V

    Thevenin's Theorem: AC Circuits with Different Frequencies

    My textbook has this excerpt: I am not sure why it refers to Example 10.6 as that is unrelated. I don't understand to be honest. How can you calculate the Thevenin equivalent at different frequencies? Let us say that you have two voltage source: v1(t)=10cos(5t) and v2(t)=10cos(2t). So how...
Back
Top