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. neilparker62

    Measurement of Hydrogen 1s 4s transition frequency

    Has this been accurately measured yet? Google searches yield results for H 1s-2s and H 1s-3s transitions but not 1s-4s.
  2. L

    S11 and Frequency Modeling for Physical Parameter

    Hi all, I am trying to obtain an empirical equation/model having 2 inputs (frequency and S11) and one output (a physical parameter) I have done various simulations using CST of the System and now I am trying to relate S11 and frequency to a physical parameter. Any suggestions of how I should go...
  3. J

    Can a harmonic be louder than the fundamental frequency?

    This is not a homework question per se, but rather something I have come across during a homework project. Using Audacity, I recorded a few different instruments playing the same notes (investigating timbre). I noticed that (using a steel string acoustic guitar) the first harmonic at 131 Hz...
  4. skepticwulf

    Importance of the frequency of AC mains power lines

    From textbook: "In much of the world (Europe, Australia, Asia) the rms voltage is 240 V, so the peak voltage is 340 V. The line voltage can vary, depending on the total load; the frequency of 60 Hz or 50 Hz, however, remains extremely steady" Why is it so important to keep it steady? what...
  5. B. Vane

    RCL Circuit: 2 Resistors, 1 Capacitor, 2 Inductors

    Homework Statement NOTE: Image uploaded with thread shows problem in clearest possible form. V = (45v)sin(80[pi] t) Resistors 1 and 2 = 50 Ohms Inductor 1 = 20 mH Inductor 2 = 2.5 mH Capacitor = 50 uF a) Find the power dissipated by each resistor. b) At what frequency will both resistors...
  6. T

    Determine source frequency and impedance

    Homework Statement The current in a series circuit of R=5 ohms and L=30 mH lags the applied voltage by 80 degrees. Determine the source frequency and impedance. (Ans: Z=5+j28.4 , f=150.4 Hz) Homework EquationsThe Attempt at a Solution Current in the inductor, IL = Vm/wL*sin(wt-80) Current...
  7. bananabandana

    Frequency difference to find a 20m whale

    Homework Statement Please see attachment for diagram. The two boats are coherent sources of sound waves (phase difference ## \phi##) - i.e it's a double slit problem. Prove the formula given for ## y_{max}##. Suppose the whale is 20m long. How large should the sonar frequency ##f## be so that...
  8. C

    Relationship between size and frequency of an oscillator

    I've always just accepted that as you scale down a mechanical system the frequency and Q factor both increase. For example, this Wikipedia page simply says that "Small bells ring at higher frequencies than large bells". But for a driven damped harmonic oscillator, what is the exact relationship...
  9. L

    Engineering Amplified Tuner Circuit, Finding Resonant Frequency

    I am looking to find the resonant frequency of the amplified tuner circuit below The equation I have attempted to use is the f = 1/2*pi*√LC With the values for the inductance capacitance being 22pF and 47mH as I believe this is the tuner part of the circuit? The value I get by inserting these...
  10. R

    Understanding frequency and dynamics

    Can someone please explain intuitively how the terms “frequency” and “dynamics” are related ? I understand the concept of each of these two individually, but I am having some difficulty visualizing what high-frequency dynamics mean. I understand the concept of how time and frequency domains...
  11. N

    Spring mass pulley system frequency equation

    Homework Statement A spring is attached to the ceiling, a pulley is attached to the other end of the spring, a string is suspended over the pulley, and a mass attached to the free end of this string. The system oscillates vertically. Can someone PLEASE help me derive this equation for natural...
  12. H

    What is the ideal damper for a passenger car suspension?

    I've been a bit lost figuring out what damper I should be using for the front suspension I am designing. Right now I'm running a wheel rate of 60 lbf/in at the front with a ride frequency of 1.2254 Hz. The front is also supporting a sprung mass of 391.68 lbf. Comfort is the end requirement of...
  13. L

    Block on a vertical spring, finding frequency

    Homework Statement A block of mass m is on a platform of mass M, supported by a vertical, massless spring with spring constant k. When the system is at rest, how much is the spring compressed? When the spring is pushed an extra distance x, what is the frequency of vertical oscillation...
  14. caffeinemachine

    MHB Finding an Infinite Binary Sequence with Average Frequency of 1's = p

    The following question came up when me and a friend of mine were discussing some basic things about probability:Let $p$ be a real number in $[0,1]$. Does there exist a sequence $(x_1, x_2, x_3, \ldots)$ with each $x_i$ being either $0$ or $1$, such that $$ \lim_{n\to \infty} \frac{f(n)}{n} =p...
  15. S

    Find maximum wavelength using minimum wavelength and frequency difference

    Homework Statement A radar receiver can be tuned to detect signals are different wavelengths. If the frequency difference between the minimum and maximum wavelength is 10 GHz and the minimum detected wavelength is 4910µm. What would be the maximum wavelength? Homework Equations λƒ=c The...
  16. A

    Frequency of damped mass-spring system

    [Mentor's note: Thread title changed to reflect question content] I really need some help with this one: 1. Homework Statement An unhappy rodent of mass 0.307kg , moving on the end of a spring with force constant 2.48N/m , is acted on by a damping force Fx=−b⋅vx. Part A If the constant b has...
  17. T

    A mass inside a horizontal spring

    Homework Statement We have a spring of length l0 tied to two vertical non moving sticks. We place a mass m at 0,45l0 and let it oscillate. If we measure the period of an oscillation, we can find the angular frequency and calculate k. The question is, how can I calculate k1 and k2, the constants...
  18. engnrshyckh

    Finding the undamped natural frequency of 2nd order system

    the following 2nd order differential equation is given: 2y'' + 4y' +8y=8x........(1) i want to find damping ratio, undamped natural frequency, damping ratio coefficient and time constant for the above system. solution: comparimg (1) with general system equaion (veriable can be exchanged)...
  19. R

    Does increasing the frequency of an antenna require energy?

    I'm under the impression that if you increase the frequency of a circuit coupled to an antenna, for the same amount of photons emitted, the frequency of those photons will increase therefore having them carry out more energy total, thus increasing the amount of energy required to power the...
  20. K

    Getting Planck's Law in terms of frequency from wavelength

    Show that Planck's law expressed in terms of the frequency f is: u(f) = (8πf2/c3)(hf/(ehf/kT - 1)) from the equation: u(λ) = (8πhcλ-5)/(ehc/λkT - 1) When I do this algebraically by simply plugging in λ = c/f, I get: u(f) = (8πhc-4)/(f-5(ehf/kT - 1) which clearly doesn't involve the correct...
  21. V

    Simulink help for getting a frequency I can use as an input

    Ok, say I have a sine wave block that has a frequency of 60Hz. What can I do to get that frequency as a number so I can use it as an input to another block? I've tried various things such as a "sign" block that counts when it switches from positive to negative and then a counter that resets...
  22. R

    Beat frequency and velocity of observer

    Homework Statement Two sound sources 15m apart producing identical 229 Hz sounds. As you move from one to the other, you hear beat frequency of 2.5. How fast are you moving?[/B] Homework Equations The question asks for the velocity of the observer Vo. The trick here is to use the standing wave...
  23. DiracPool

    Frequency oscillations and Planck's constant

    This is a two part question and something I think I should know off the top of my head, but I don't, and I can't find a ready answer to it on at least a cursory search. The first part has to do with defining a frequency of a wave in general. I can sit here and tap out a beat on a drum that...
  24. A

    Finding Harmonic Vibration from Frequency

    can we find the harmonic of vibration somehow just by knowing frequency?
  25. S

    How to calculate natural frequency of a circular plate

    I am trying to get used to using a Data Physics analyzer at work in order to measure the natural frequency of components of a larger project I am involved in, my method described is intentionally crude as I was trying to do this as a quick play around before diving into the real thing.. To...
  26. E

    High Frequency Servo shielding and grounding on robot?

    I have an issue that appears to be relating to noise mitigation and grounding. Some background on myself is I have a mechanical engineering technology degree. But my job requires an ability to work with and troubleshoot electrical issues. Currently a customer is using a Servo motor on an end...
  27. D

    Frequency dependence of gravitational acceleration

    Imagine a massive object emitting photons of various frequencies. Because the object is massive, it will exert gravitational acceleration on those photons. Because the energy of a photon is proportional to its frequency, it seems that higher-frequency photons will experience a higher magnitude...
  28. S

    MHB Modifying frequency to eliminate 0

    The start of the solution says to modify the Poisson to eliminate the case of 0 profit. I don't understand why this is the case or how to identify this type of problem as such. I don't see another way to reach the solution either... Thanks!
  29. X

    Find frequency of electromagnetic waves

    Can anyone give a solution or guidance about how to solve this. In vacuum, the components of an EM wave are Ey = 50(V/m)cos[(5.00 m-1)x + ωt], Ex = 0, and Ez = 0. What is ω?
  30. K

    How can I fine tune an ultrasonic frequency?

    I'm building an ultrasonic drill, and I've already collected or machined all of the components. Since I'm very inexperienced in electronics, I'm planning to simply buy an ultrasonic driver (power source) rather than build one myself. The one I'm interested in is here...
  31. great1122

    I have a question on the phase of a frequency response

    Hello, I'm currently studying for an exam and came across a question I can't seem to figure out. How exactly do we go about calculating the phase of a frequency response. Here is the question, it for part A) iii. Here are the answers to the other parts and the sketch of the magnitude: I know...
  32. M

    Power Formula: Frequency & Electrical Power Explained

    We all know that the electrical power = V * I * cos Q. and I know how this formula is derived. but yet intuitively I was expecting to see the frequency in the formula. I just need intuitive explanation how the frequency is not appearing in the power formula while we know in physics that higher...
  33. M

    Please help my son year 12 physics -- frequency and wavelength

    my son is trying to find out how he can find an answer by being shown how to do the working out he wants to find out what the wavelength is if he only has the hz if he is 93.4 hz how does he find out what the wave lenth is thanks
  34. T

    Improving Frequency Resolution with Window Functions in FFT Calculations

    Okay I have a question involving calculating the FFT of a signal from a sensor. I have simulated many different scenarios in MATLAB of various noise characteristics involving the signal. I want to take the FFT of a noisy signal. As long as my expected input signal has a higher amplitude than...
  35. 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...
  36. Kevin Spacey

    Describing how to make a standing wave?

    I'm struggling in physics class, and I really need help with this question. "If you are holding a spring in your hand and making waves, describe how to make a standing wave at the 2nd resonance frequency (next frequency over the fundamental). Include a sketch with your answer." What does this...
  37. R

    Does reflection change the frequency of light?

    Note that I am not addressing only specular reflection here, but both kinds. Anyway, so if I had light of a certain frequency incident upon a surface, will the light that reflects off that surface also have the same frequency? That would imply that it had retained the full 100% of its energy...
  38. F

    Natural frequency of 3 coulomb force bound particles in EF

    Homework Statement I was given a task to model (using Matlab) 3 identical particles in external field and find spectra of lowest system energy states using gradient descend method for each particle in the system. I did a run of 500 random generated coordinates and found this distribution...
  39. synMehdi

    Speed of EM wave depending on the frequency

    I know that in a vacuum, speed of light is constant. My question is more about the speed of light in a material like air. Dispersion of light in a prism tells us that the speed of light or the material index depends on the wavelength ( or frequency which is constant ) so I thought that air...
  40. S

    Calculating Frequency of Siren Heard by Truck After Police Passes

    Homework Statement A truck moving at 36 m/s passes a police car moving at 45 m/s in the opposite direction. If the frequency of the siren relative to the police car is 500 Hz, what is the frequency heard by an observer in the truck after the police car passes the truck? (The speed of sound in...
  41. STEMucator

    Dividing the CLK frequency by 8

    Homework Statement The question and provided answer are given: Homework EquationsThe Attempt at a Solution I disagree with the answer. Shouldn't there only be three rising edge triggered d flip-flops? I say this because I know if I only had one d flip-flop with the inverter, the clock...
  42. B

    How to Calculate Ringing Frequency for a Snubber Circuit in a Buck Converter?

    may i know how to calculate ringing frequency?
  43. R

    Frequency & Eigenvalue from dynamic eqn

    Hi, i am trying to find the natural period of a vertical cantilever beam which is fixed at bottom and free at other end., i worked out the global M & K matrices and i have the eqn in the form [M]-w^2[K] = 0, the M & K are not diagonal matrices, but square symetric matrices of rank 6. i...
  44. Phynos

    Finding frequency of moving sources with beats

    Homework Statement Jane waits on a railroad platform while two trains approach from the same direction at equal speeds of 11 m/s. Both trains are blowing their whistles (which have the same frequency), and one train is some distance behind the other. After the first train passes Jane but...
  45. G

    Proportionality relationships in Mersenne's Law

    Hello. Is anyone able to explain the 3 proportionality relationships present in Mersenne's Law, specifically in a conceptual sense? Mathematically they are easier to understand however it is difficult to understand them conceptually relating to strings. Any help would be appreciated. :)
  46. Aafia

    What is the Cut-off Frequency and How Does it Affect Signal Processing?

    This term is new for me so explain it simply ... and give a simple definition about cutt off frequency
  47. L

    Calculating Chemical Shift: How do magnetic fields affect NMR frequencies?

    Homework Statement In an NMR spectrum a CH2 group has a peak centred at 9.81 ppm. What is the shift in Larmor frequency of the protons from that of an unshielded proton if the spectrometer magnetic field is 9.4 T? The magnetogyric ratio of an unshielded proton is γH = 26.75 × 107 rad s-1T-1 2...
  48. S

    What Was the Initial Frequency of the Trumpet Player?

    Homework Statement A trumpet player hears 3 beats per second when she plays a note and simultaneously sounds a 440 Hz tuning fork. After pulling her tuning valve out to slightly increase the length of her trumpet, she hears 5 beats per second against the tuning fork. What was her initial...
  49. C

    Worst frequency for EM interference?

    So I have some big speaker amplifiers at home, and they sometimes pick up radio interference from the CB enthusiast next door (he uses AM, so I'm guessing this is inducing a signal inside my amplifier which amplifies it into my speakers). It isn't really a big problem so I'm not looking for a...
  50. A

    Understanding EM Spectrum: Emitting vs. Reflecting | IR Camera Examples

    Hello, I was wondering how one would be able to tell the difference between an object emitting a certain wavelength of the EM spectrum, vs. an object reflecting that same wavelength of the EM spectrum. For example: 1) Suppose I have an IR source at 7 microns. I point this source at water, and...
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