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. Pushoam

    Range of frequency of electromagnetic waves

    Theoretically speaking, does the frequency of em wave range from 0 to infinity?
  2. W

    Flute player initial frequency?

    Homework Statement A flute player hears four beats per second when she compares her note to a 587 Hz tuning fork (the note D). She can match the frequency of the tuning fork by pulling out the "tuning joint" to lengthen her flute slightly. What was her initial frequency? Homework Equations Not...
  3. O

    What is the relationship between frequency range and GBW in amplifiers?

    I have an op-amp with frequency range 20Hz - 20kHz. Is frequency range the same as bandwidth?
  4. ltnghia1304

    The frequency of two parallel springs and one weight system

    Homework Statement I want to find the angular frequency of the system below Homework Equations F = -kx U = 1/2*k*x^2 The Attempt at a Solution But here's the answer: I don't know how come this solution. Any one help me? Thank you so much.
  5. D

    What Is the frequency of red light?

    Homework Statement The speed of light in a vacuum is 3.00x(10*8)m/s. Using the equation v=fxλ, calculate the frequency of red-light. (I was told to use the wavelengths given from textbook) Wavelength/λ =700nm v=300,000,000 <-- ( I need help understanding this. Is this a rate? Or?) Homework...
  6. Mzzed

    Superposition's effect on frequency?

    Imagine two electromagnetic waves are traveling in opposing directions such that they eventually meet, overlap, and continue traveling as usual after the superposition/overlapping event. Just before they overlap there is some superposition effect taking place but not enough to fully merge the...
  7. RyuuJin

    A Gravitational waves: effect of frequency on strain

    Hi guys. I am having a little trouble understanding a few relations professor mentioned at lectures, regarding gravitational waves - flux of energy and strain. First one expresses how is the flux of energy F related to frequency of radiation f and inflicted strain h. And the second one is for...
  8. G

    Sound absorption coefficients differing with frequency

    Hi there, my understanding of absorption coefficients is that harder materials generally reflect more sound similarly to how a harder material will result a ball to bounce higher than a softer material. What I am having trouble finding research on and understanding is the reasoning behind the...
  9. I

    Why don't I hear beats when singers or instruments play the same note?

    Consider this: two singers are both singing an A4. These singers, like any human, are not perfect. One sings 440 Hz and one sings 441 Hz. So, theoretically, I should hear an amplitude oscillation with a frequency of one second, right? I never seem to hear this kind of effect, though it should...
  10. O

    Can Power Lines Transmit Radio Signals in Emergencies?

    Our street electric power lines have frequency of 50 Hz or 60 Hz.. what would happen if you increase the frequency higher to radio frequencies or microwaves.. would current still flow? and can you make it as antenna for emergency transmission?
  11. K

    Natural frequency of pulley system

    Homework Statement https://www.physicsforums.com/attachments/197474 Homework Equations 3. The Attempt at a Solution [/B] ma + kx = 0 I know how to do it if the spring is in the middle of the pulley, not using energy method. by the free body diagram. But I am stuck at this. [Updated: I know...
  12. flamespirit919

    Frequency of Vibration of Two Masses Joined by a Spring

    Homework Statement Two masses ##m_1## and ##m_2## are joined by a spring of spring constant ##k##. Show that the frequency of vibration of these masses along the line connecting them is: $$\omega =\sqrt{\frac{k(m1+m2)}{m1m2}}$$ Homework Equations ##x(t)=Acos(\omega t)## ##\omega...
  13. whatphysics

    Amplitude spectrum vs frequency spectrum

    What is the difference between amplitude spectrum and frequency spectrum? In signals and systems.
  14. R

    MATLAB Frequency domain filtering in Matlab

    I am trying to implement several filters in Matlab for Fourier domain filtering. They are the cosine, Shepp-Logan, and Hann/Hamming window filters. These filters are defined as multiplying the ramp filter by the cosine function, sinc function, and Hann/Hamming windows respectively. This is how...
  15. jlmccart03

    Finding frequency of an AC current sin wave?

    Homework Statement An AC current is given by I= 475 sin( 9.43 t), with I in milliamperes and t in milliseconds. Find the frequency. Homework Equations w = 2pi*f The Attempt at a Solution I got 9.43/2pi which is 1.5 Hz, but that is wrong. I honestly have no idea what to do to find the Hz.
  16. W

    Get vibration frequency form absorption spectra line

    Homework Statement [/B] "Absorption spectra of gaeous HCl show a line at 3.5 μm which results form molecular vibration (oscillation from interatomic distance)" How do I get the frequency of vibration from this? Homework Equations ? If I knew this, then I could probably solve the problem The...
  17. J

    Frequency Division Multiplexing in Telephone

    "A standard FDM scheme for telephone signals is to multiplex 12 voice channels, each occupying 4kHz bandwidth, into a group signal with 48kHz. The next basic building block is the 60-channel supergroup, which is formed by frequency division multiplexing five group signals. The next level of the...
  18. Andre Teixeira

    I How to obtain the resonance frequencies of a given material?

    The frequency of plasma already achieved ... in a study, is presented the resonance frequency in eV, how to obtain in Hz? Wo = 7eV
  19. M

    Constant frequency of light and connection to QM

    Could someone provide a good explanation as to why light's frequency doesn't change under refraction? The textbook I'm using gave us a two step derivation and I don't really feel like it did a proper job in explaining anything (it's Haliday). Also, a slightly *crackpot* follow up question -...
  20. S

    Low Pass: Why did my professor use frequency and not angular frequency?

    Homework Statement We are given a passive RC low pass filter with an input voltage of 5 Vrms at a frequency of 1 kHz. The resistor has a value of 22 kΩ, the capacitor a value of 100 nF. There is a current i across the resistor. (see picture below) We are to calculate the magnitude and phase...
  21. R

    Determine the angular frequency of the system in SHM

    Homework Statement Determine the angular frequency of the system in the image. The cable is ideal but the pulley is not. I will present the same solution but with different coordinate axes. For some reason they arent the same and neither of them are correct. Given data: R is the radius of...
  22. Poetria

    Find Resonant Frequency of Spring-Mass-Dashpot System

    Homework Statement Consider the spring-mass-dashpot system driven by a sinusoidal force on the mass: (mD2+bD+k)x=F where sin(omega*t) Recall that for the unforced underdamped oscillator (b^2<4km, F=0), the value of the natural damped frequency omega_d=sqrt(k/m - b^2/(4m^2) Find the resonant...
  23. T

    What Frequencies Emerge in an AM Signal with Given Parameters?

    Homework Statement Which frequency components are present in the amplitude-modulated (AM) signal A(t)=[1+asin(2πfmt)]A0sin(2πfct), where fm= 3.5 kHz, fc = 540 kHz, and a = 0.1? Homework Equations A(t)=[1+M(t)]A0sin(2πfct), where modulating signal M(t) = sin(2πfm t + ∅), high frequency carrier...
  24. stevendaryl

    A Relative frequency and nonmeasurable sets

    There is a conceptual puzzle that I don't understand about nonmeasurable sets. Take the unit interval [0, 1] and let S be some subset. Now, generate (using a flat distribution) a sequence of reals in the interval: r_1, r_2, r_3, ... Then we can define the relative frequency up to n as follows...
  25. S

    Does frequency affect inductor and capacitor value

    Hi , I was measuring the inductor and capacitor value of a resistor bank with a 100Hz and 1kHz using a LCR meter by fluke. I realize that with different frequency, the L and C values were different. If the measured values were the inductance and capacitance I can understand that it changes...
  26. Conductivity

    Effect of frequency and intensity on PE

    if two light with different frequency have the same intensity then the PE current is the same. But that doesn't make sense, and some graphs show that if you increase frequency while intensity is constant, the current increases up to a point then drops. A couple of old threads, people mentioned...
  27. S

    How Does Load Cycle Frequency Affect the SN Curve?

    Hi, What is the effect of the load cycle frequency on the SN curve (Wöhler curve)? Especially when the frequency matches the natural frequency of the component/material? Instinctively, I would think that at the natural frequency the number of load cycles until fracture is lower than at any...
  28. S

    AC Current in GHz Frequency and Zero Resistance

    Hello Experts, I am a physics newbie with big ideas. I have a question. I am thinking about how to produce a zero Resistance Current. We know we can do this using super-conductors in sub zero temperature, but maybe there's another way. My assumptions (which could be wrong): 1) Resistance in a...
  29. C

    Open Circuit Termination for Waveguides in High Frequency Labs

    Hi everyone, I am trying to understand that why do we use open circuit terminator for wave guides or any RF element such as coupler and etc. I know if we just leave it open, it does not work as open circuit. But why?
  30. R

    Finding wavelength and fundamental frequency with string

    The length of a string is 1328 cm. It is held fixed at each end. The string vibrates in eight sections; i.e., the string has eight antinodes, and the string vibrates at 97 Hz. Find the wavelength and fundamental frequency. I have no clue, anything helps! Thank you!
  31. R

    A Converting Partial Differential Equations to Frequency Domain

    Hello All, I would like to convert a partial diff equation in time domain into frequency domain, however there is a term of the form: Re(∇(E1.E2*) exp(j[ω][/0]t)) where E1 and E2 are the magnitudes of the electric field and [ω][/0] is the angular frequency. Can someone please help me to...
  32. Theudius

    Does Frequency Change in a Medium?

    Hi I was told by physics lecturer that both the wave speed and wave length of light changes when it enters a medium, however I questioned this stating that if both wave speed and wave length changed then frequency must also according to the formula c = fλ. He stated that "frequency is energy...
  33. T

    SHM Amplitude vs. Frequency graph

    Homework Statement A metal hangs vertically from one end of a spring. The other end of the spring is tied to a thread that passes over a pulley and is attached to a vibrator, as shown in the figure. The vibrator is now switched on. The frequency of vibration is varied from 0.7f to 1.3f where...
  34. T

    Finding the angular frequency of an object

    Homework Statement An object undergoes simple harmonic motion along an x-axis with a period of 0.50s and amplitude of 29mm. Its position is x = 12mm when t = 0s. Determine the value of ω in the equation of motion. Suppose that ω > 0. Homework Equations $$ω = \frac {2π} {T}$$ The Attempt at...
  35. V

    MHB Flood Frequency & Return Interval: 100-Year Analysis

    if in 100 years of records you have had floods in five of those years is the flood frequency 5 per 100 years ? and would the flood return interval be every 20 years?
  36. S

    Block on Spring SHM, Finding angular frequency

    Homework Statement An "ideal" spring with spring constant 0.45 N/m is attached to a block with mass 0.9 kg on one end and a vertical wall on the other. The floor has negligible friction, and you give the block a push and then let go. You observe that the block undergoes simple harmonic motion...
  37. H

    Natural Frequency for torsional vibration

    I am trying to calculate natural frequency for torsional vibration of fixed fixed beam using following formula. =1/2*3.142 sqrt(K*g/mr^2) hz Where K=J*G/L and G=Modulus of rigidity g=acceleration due to gravity=386.4 in/se2 m=mass hanging on the beam at distance 'r' from the longitudenal...
  38. T

    Sound & Music, String Frequency

    Homework Statement Suppose a string is 0.50 m long, it has a mass per unit length of 1.2 g/m, and it is under a tension of 52 N. What is the frequency of the second mode of this string? Express your answer in the SI unit for frequency? Homework Equations f = Vs/2L Vs = sqrt (F/μ) The Attempt...
  39. D

    Problem Related to Beat Frequency of a hollow tube

    Homework Statement Q. A hollow metallic tube closed at one end produces resonance with a tuning fork of frequency n at temperature T. The temperature of the tube is increased by dT. If the coefficient of thermal expansion of the tube metal is alpha, the beat frequency will be - (there are 4...
  40. L

    Does anybody know the sampling frequency of a cop radar?

    More specifically, does anybody know the sampling frequency of a mounted 360 degree cop radar? NOT a conical/directional hand-held radar gun.
  41. J

    Wavelength and Frequency in a Waveguide

    The problem states that the wavelength and frequency in a waveguide are related by: ##\lambda = \frac{c}{\sqrt{f^2 - f_0^2}}## then asks to express the group velocity ##v_g## in terms of c and the phase velocity ##v_p = \lambda f## Solution: Given that ##\omega = 2\pi f##, ## \omega(k) =...
  42. T

    Sound & Music - Ptolemy Reduced Frequency

    Homework Statement This is a homely. We were instructed to make a monochord and find and mark C5, G4, F4, E4, D4 & C4 by multiplying our starting length with the length rations (C5 = 1/2, G4 = 2/3, F4 = 3/4, E4 = 4/5, D4 = 8/9, C4 = 1) Then we used "Ravenlite" the application to measure the...
  43. Cocoleia

    Frequency domain and mesh currents

    Homework Statement Homework EquationsThe Attempt at a Solution So far I was able to transform each element into the frequency domain: I am just unsure how to work with the dots to find the mesh currents. Can someone explain? Thanks.
  44. C

    Determine the natural frequency

    Homework Statement Determine the natural frequency in Hz of the system sketched below given the following values: Mass m=4kg Spring stiffness k=28kN/m Length a=121mm Length b=93mm Homework Equations ω=(k/m)^0.5 The Attempt at a Solution so probably I need to find m should I multiply...
  45. Nikhil N

    EMI(Electro Magnetic Interference) Magnitude and Frequency

    I want to analyze the efficiency of my data communication between slaves and master in the presence of interference. The protocol what I am using is modbus, with baud rate of 9600 , I am using 1000 ft cable. What I am struggling to do is, how to couple the noise into the cable in a way it is...
  46. D

    Natural frequency of an Oscillating water column device

    Homework Statement Assuming that an OWC device is floating/moored in monochromatic waves. When there isn't air pressure distribution inside (atmospheric condition) the device behaves as an undambed body (with the oscillating chamber open to the atmosphere). When there is air pressure...
  47. Jordan ray

    Varying frequency of an LED drive circuit

    Greetings. How would I go about finding a way to use an audio signals frequencies to control the positive connection on a 12v dc led circuit? In other words, have the visual effects you get hooking up a dc led strip to an amplifier, but instead controlling the dc positive output to the strip...
  48. T

    A Investigating Velocity & Frequency Widths of Megamasers

    I was going through http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?2001ASPC..249..639B&defaultprint=YES&filetype=.pdf where the velocity of the maser is on the order of 80 000 km/s due to cosmic expansion (z = 0.265). But as you may see in Figure 1, the velocity width of the...
  49. mccoy1

    I The absolute value of the frequency in quantum mechanics

    I was reading Bransden's Quantum Mechanics 2nd edition, chapter 2 page 61. There,it says "It should be noted that since E =hv (v for nu), the absolute value of the frequency has no physical significance in Quantum mechanics..." Why is that? Isn't this a contradiction?
  50. W

    Doppler effect with frequency ratio

    Homework Statement An avant-garde composer wants to use the Doppler effect in his new opera. As the soprano sings, he wants a large bat to fly toward her from the back of the stage. The bat will be outfitted with a microphone to pick up the singer's voice and a loudspeaker to rebroadcast the...
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