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. J

    What is the beat frequency for a cyclist ringing a bell towards a wall?

    Homework Statement A cyclist with a bell ringing with a frequency of 659.7 Hz drives towards a wall with a speed of 8.15 ms-1. Just before colliding with the wall the cyclist hears beats, due to the bell itself and the reflection of the sound from the wall. What is the frequency of beats...
  2. Maximtopsecret

    Lorentz transformation of frequency

    Homework Statement Light (plane wave) reflects from the mirror moving along X-axis with speed V. The wave is orthogonal to the mirror (φ=0°). Write the law for frequency change. Homework Equations I know Lorenz transformation for frequency. The Attempt at a Solution All I do not know is how to...
  3. Mentz114

    Frequency shifts in rotating frames

    After the recent discussion here about the Sagnac effect** I wanted to see if there is any frequency shift if light is sent from one point on a rotating worldline to another a small distance away. It looks like this cannot happen because ##\gamma=dt/d\tau## is the same at every point on the...
  4. A

    Determine resonant frequency of an AC voltage source

    Homework Statement Given a series RLC circuit, with one R, one L, and one C element, and an AC voltage source with variable frequency, find the resonant frequency experimentally given an ammeter and a voltmeter. Homework Equations The current in the circuit when the circuit is in resonance is...
  5. J

    A question about resonant frequency

    hello, I'm a first year science undergrad, currently learning about mechanics and waves and so on there's this vine that's been going around, which shows someone playing a harp - here is the video in question; I personally find it quite beautiful and fascinating. Apparently the phenomena is...
  6. Rampart

    Finding Frequency Cutoff in a Breadboard Circuit: Tips and Techniques

    Hello there.I have a question about how to find the frequency cutoff in a breadboard with oscilloscope,multimeter etc Ok the circuit it simple.Ac voltage source in series with a resistor,which is in series with a capacitor.I am given that in the frequence cutoff the voltage of the capacitor is...
  7. M

    Calculating Cyclic Energy from Acceleration (Relative)

    Hello, I am looking at relating two situations under which cyclic energy is applied to a material. Condition 1: A material has been subjected to a force of 1G at 0.1Hz for 47 days. Condition 2: The same material has been subjected to a force of 4.5G at 60Hz for 3600Seconds. Is it possible to...
  8. GM Jackson

    How does a black body emit as much energy as it absorbs?

    Homework Statement A black body absorbs all incident electromagnetic radiation, including visible light which has wavelengths from 380nm to 750nm. IR radiation has wavelengths that are so long they are measured in microns. That suggests that visible light has a higher frequency than IR, and...
  9. E

    Beat frequency and length question. (grade 11)

    Homework Statement Two pipes, Identical in length and closed at one end are producing notes. You are very, very annoyed because the notes are creating an audible beat frequency of 20Hz. If one pipe is producing a note at 10Hz and the temperature is 15C (which correlates to a speed of sound of...
  10. Salvador

    Mysterious Low Frequency Horns: Real or Fake?

    Does anyone have an explanation for these? youtube is filled with videos about them and as many could be fun tricks played by trolls many are also real confirmed in many news media articles heard by witnesses. for example I have heard some physicists explaining them as electromagnetic waves...
  11. U

    Redshift in Frequency - Universe

    Homework Statement (a) Show the relation between frequency received and emitted (b) Find the proper area of sphere (c) Find ratio of fluxes Homework EquationsThe Attempt at a Solution Part (a) Metric is ##ds^2 = -c^2dt^2 + a(t)^2 \left( \frac{dr^2}{1-kr^2}+ r^2(d\theta^2 + \sin^2\theta)...
  12. G

    Relation between Energy and frequency

    Hi Friends! Please tell me if the question below is valid? "If the frequency of the source is changed from f to 2f ,keeping amplitude same,then total energy is changed by what amount?" What I conclude is"We can think it in two ways: 1 In classical sense,where I could not find any...
  13. baby_1

    High Frequency Transistor Tutorials

    Hello As I read all the above links of Wikipedia about HEMT I have many problems to know better about these kinds of transistor.could you introduce me a good tutorial about HEMT transistors? Thanks
  14. U

    Frequency of Photon in Schwarzschild Metric?

    Homework Statement The schwarzschild metric is given by ##ds^2 = -Ac^2 dt^2 + \frac{1}{A} dr^2 + r^2\left( d\theta^2 + sin^2\theta d\phi^2 \right)##. A particle is orbiting in circular motion at radius ##r##. (a) Find the frequency of photon at infinity ##\omega_{\infty}## in terms of when it...
  15. R

    How frequency domain topic should be taught in the academic course?

    This is a soft question but I think it's a real fact.The Frequency domain has made revolution in the field of Mathematics,Physics,Digital Signal and image Processing etc. Some of concepts which are very difficult to analyse in spatial or time domain can be very easily understood in the frequency...
  16. G

    Center Frequency and Bandwith of Bandpass Filter?

    Homework Statement Determine the center frequency and bandwidth of the bandpass filter. Homework Equations center frequency of bandpass filter = ωc occurs when the magnitude of H = 1 H = V0/Vs Center frequency occurs when Im(Z) = 0 Zc = 1/(jωC) = 1/s ZL = jωL ZR = R I don't know a formula...
  17. P

    How to obtain the differential distribution frequency

    good day all. Please can I see the maths calculation involved in obtaining the differential distribution frequency fm(D) in the attachment.many thanks
  18. R

    Frequency: Electromagnetic waves

    Are the angular frequency in electromagnetic waves and frequency of a photon characterise the same physical quantity? I know that these come under two different theory, but I want to know whether these names (angular frequency of em wave and frequency of photon) mean the same physical quantity...
  19. S

    Transfer Function vs Frequency Response Function

    Ive read other threads on here about this and am still slightly confused about it. I did a little experiment; and I am hoping someone can help shed some light on the results. The experiment: 1. Create a system: modeled after a simple spring-mass-damper with mass=1 damping zeta=.1, natural...
  20. P

    Obtaining Differential and Cumulative Distribution Frequency

    hello all.glad to be here! please in the attached document, column 5 and 6 which represents the differential and cumulative frequency distributions were obtained using equations (5) and (6). I'll be mighty grateful if anyone can give me a step by step breakdown of how it was done?? Many thanks...
  21. B

    Resonant Frequency shift of bimorph piezo structure

    Hi, folk~ I fabricated bimorph piezoelectric shear stress sensors. When air flow applied, there were resonant frequency shifts to left side (decreasing) and impedance decrement in resonant frequency as well . So even though I am suspecting that kinds of results as because of damping effect...
  22. DonkeyB

    Oscillator/spring quality vs frequency....

    I apologize in advance for not being physics savy. My question stems from my interest in loudspeaker behavior, but I think I need to clear up some more basic physics. I'm trying to understand what determines the Quality factor of an oscilator/resonator. Given 2 system's with identical spring...
  23. Salvador

    Generator output frequency and rpm

    Hi, as I was reading on generators I noticed that apart from the homopolar machine(faraday disc) all other generators are basically AC , or if they are DC then the very current generating loop or part involves changing and time varying currents. They usually have poles on the rotor or stator...
  24. S

    Finding the frequency of small oscillations given potential energy U

    Homework Statement The potential energy of a particle of mass m near the position of equilibrium is given by U=U0sin2(αx) where U0 and α are constants. Find the frequency of the small oscillations about the position of equilibrium. Homework Equations Work energy equation...
  25. V

    Calculating half power frequency/cutoff frequency

    Homework Statement *(Problems attached as images)* For first problem: ##\cfrac{|V_2|}{|V_1|} = \cfrac{1}{\sqrt{4+(\omega RC)^2}}## For second problem: ##\cfrac{|V_2|}{|V_1|} = \cfrac{\sqrt{1+(\omega RC)^2}}{\sqrt{4 + (\omega RC)^2}}## I have to calculate half power frequency for both...
  26. S

    YBCO Phonon Frequency: Hole Doping .2, 75-70°K @ 70°K

    I was hoping someone could tell me the phonon frequency of the electrons for YBCO with hole doping of about .2 and a critical temperature of around 75-70°K at about 70°K. An answer in Hz would be preferred, or failing that, in cm-1 with the wave speed. Also, might the Kohn anomaly influence the...
  27. E

    The Importance of Gravitational Frequency Shift in GPS Measurements

    I have been studying the "fallen" photon experiment, in which the frequency of a photon changes as it falls through a height H. f'=f_0(1+\frac{gH}{c^2}) It is often stated that this is a huge factor in the application of GPS. However, I do not understand why. I understand that the photon will...
  28. A

    Mathematical relation between dipole moment and frequency?

    how can we relate innermost stable circular orbits, keplerian, epicyclic, frame dragging precession frequency with dipole moment.
  29. Aristotle

    Finding the Uncertainties in Frequency with Given Capacitor and Inductor Values

    Homework Statement I am given a frequency value of 95 GHz (9.5x10^10 Hz), C= 25 F, L=1.12x10^(-25) H. The question is to find the uncertainties in frequency by taking account of inductor being 5% accurate & capacitor being 8% accurate. Homework Equations I believe this is the correct formula...
  30. M

    Speed and Frequency of Waves Lab

    I recently had a lab in physics class that I was a little confused about. I posted a picture of a couple parts of the lab including the instructions and a couple of questions. I also highlighted a few things that confused me. In the instructions it said that all objects vibrate at a set of...
  31. B

    Why natural frequency conveyors are not dangerous?

    I've read that natural frequency conveyors are very efficient because the drive only compensates for the amplitude that's lost in the elastic supports. Could you please explain how is this different from working at resonant frequency which is so dangerous? P.S. What kind of analysis should I...
  32. C

    Calculating the Frequency of Vertical Vibration in a Bouncing Car

    Hi, I hope somebody can help me.I'm stuck in this problem..I want to make sure I made it right before sending to the teacher.Thank you very much 1. Homework Statement An 80.0 kg student sits down in his 920 kg car, and his weight causes the causes the car's springs to sink an additional 4.0 x...
  33. goonking

    What is the frequency of oscillation for a human leg as a pivoting rod?

    Homework Statement Consider a human leg to be a rod of uniform density pivoting about one end. What will the frequency of oscillation be for a leg with a length of 0.82 meters?Homework Equations I believe we need the imagine the leg as a rod, so the moment of inertia would be = 1/3 m L2 The...
  34. S

    Why does collision frequency decrease with increasing T?

    From the equation for Z from this website...
  35. I_am_learning

    Absurdly high Frequency resolution of function generators?

    I checked some common commercial high-quality lab function generators and they seem to provide frequency output upto 50 Mhz (not a big deal), but with resolution of 1 uHz ! That means, they can generate signal with 50000000 Hz and also with 50000000.000001 Hz ?? That would equate to time-period...
  36. goonking

    What Is the Oscillation Frequency of a Weight Hung on a Spring?

    Homework Statement If I attach a spring to the ceiling, then hang a weight on the spring, the spring extends by 1.19 meters, comes to rest for an instant, and then begins oscillating. The mass of the weight is 6.6 kg. What is the oscillation frequency of the block's oscillations. Homework...
  37. Y

    Doppler effect and Beat frequency

    Homework Statement A runner is running with speed V along the straight line connecting two identical speakers. Both speakers are playing a tone of the same frequency f. a)What is the beat frequency that the runner hears? b)If the standing wave forms between two speakers, how frequently will the...
  38. B

    What are the features of natural frequency vibro-conveyor?

    I'm considering two types of vibrating feeders, brute force and natural frequency. Can you tell me how natural frequency conveyor works? What kind of design should I choose to transfer light materials? What If I want to use an upwards angle, how do I determine that upward going path of...
  39. alejandro ureta

    Light Sensors: Color to Frequency

    Hi all, I‘m a recent member in this forum, very glad I found it. I am interested in light sensing and would like to know if there is any sort of light sensor whose response is manifested and measurable as an emmisson frequency similar to the frequency which is receiving or sensing. I am...
  40. F

    What is the frequency of the wave?

    1. A sound wave of the form s = sm cos(kx - ωt + φ) travels at 345 m/s through air in a long horizontal tube. At one instant, air molecule A at x = 2.00 m is at its maximum positive displacement of 6.30 nm and air molecule B at x = 2.09 m is at a positive displacement of 2.40 nm. All the...
  41. 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.
  42. 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...
  43. 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...
  44. 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...
  45. 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...
  46. 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...
  47. 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...
  48. 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...
  49. 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...
  50. 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...
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