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. MedEx

    Find the Driving frequency and phase angle for this R-C phasor problem

    Using the givens I found ωd=862 rad/s, and with some help I got tanϕ=-1 and Z=56.5685 ohms. But I can't figure out any of the other variables. I'm not even exactly sure what "driving frequency" is and I can't find an equation for it.
  2. T

    MHB Frequency Distribution: Time Reading Political Blog

    The data represent the​ time, in​ minutes, spent reading a political blog in a day. Construct a frequency distribution using 5 classes. In the​ table, include the​ midpoints, relative​ frequencies, and cumulative frequencies. Which class has the greatest frequency and which has the least​...
  3. J

    Standing Waves: Incident and Reflected Waves' Equal Frequency

    I learned that standing waves form when the incident wave's frequency is equivalent to the reflected wave's frequency. But I also learned that according to Newton's 3rd law, when a wave hits a boundary, the reflected wave continues to travel in the opposite direction but has equal frequency and...
  4. Y

    Is the propagation velocity slow down at low audio frequency?

    I uploaded the paper from Belden cable company. It said the velocity slows down to 5EE6 m/sec from 1EE8 m/sec at RF speed. I don't remember I ever read this before, I thought velocity = 1/sqrt( μ/ε). Please give me a link on the reason if this is true. Thanks Alan
  5. J

    Calculating the frequency of an electron orbiting in a magnetic field

    So my thought process is as follows, since the initial centripetal force and the second magnetic force are working together, we can set up an equation to calculating final frequency. However, I am struggling with how this can be done given so little numbers. mvi^2/r + qvB = mv^2/r Am I on the...
  6. M

    How Does Resonance Frequency Affect MEMS Accelerometer Performance?

    Hello, I am designing a resonant mems accelerometer. It has a resonating beam. We are actuating it by AC voltage + DC voltage. We are going to actuate it at beam's resonance frequency. When I search for papers related to previous studies, I encounter resonance frequencies ranging from 20 kHz to...
  7. S

    Is frequency increased when pulsed?

    Explanation: Let's say I have something generating a frequency of 60hz. If I pulse that frequency on and off, 10 times a second, does that amplify the distance that wave will travel through space? Let's assume the medium it is traveling through is consistent for the moment. If the 60hz...
  8. JosephTraverso2

    Area under a frequency vs wavelength graph?

    Homework Statement Hi Everyone, So I'm doing writing up my weekly physics lab report and I had an idea to better present my findings. I have a chart displaying the frequencies of numerous tuning forks as well as their experimentally determined wavelengths and I have to find the speed of sound...
  9. G

    A Frequency threshold in the photoelectric effect

    The existence of a frequency threshold in the photoelectric effect is often regarded as the strongest objection to the wave theory. Because?
  10. R

    Why is my thinking incorrect? -- Block and spring driven by a motor

    Homework Statement An oscillator consists of a block attached to a spring (k=400n/m). At some time t, the position (from equilibrium), velocity, and acceleration of the block are x= .100m, v= -13.6m/s, a= -123m/s^2. What is the frequency? mass of block? amplitude. Homework Equations position...
  11. CivilSigma

    Harmonic Load in the Time and Frequency Domains

    Homework Statement For any harmonic load: $$F(t)=F_0\cdot \sin(\omega t)$$ What is the corresponding Frequency domain equivalent? My lecture notes is suggesting: $$ F(t)=F_0 \cdot e^{i \omega t} $$ But I am failing to see how they are equal? The lesson is about Stochastic Response of...
  12. J

    What is the maximum or Nyquist frequency of a Gaussian signal?

    Hello. I'm studying Fourier analysis. If we look at attached graph where Gaussian functions are transformed by Fourier analysis, we can find Gaussian functions in frequency domain have maximum value at 0 hertz. So I confused what is the Nyquist frequency at Gaussian signal. I need to know...
  13. R

    Chemical structure vs excitation frequency (photons)

    Is there a text, or set of texts, on how to predict what frequency of photon is released when a particular molecule is brought to an excited state and then relaxes? So for example if you were to put, say, benzene into an electrical tube and excite it what frequency would be released and more...
  14. H

    Why do higher frequency light waves bend more in a prism?

    For example, why does blue light refract more than red light in a prism?
  15. U

    MHB What is the relationship between frequency and angular speed?

    Hello there, I'm new here and i need some help on my home work. A DVD drive rotates at an angular frequency of 4800 rpm. a) what is it's angular speed in rpm? b) at 4800 rpm, what is the linear speed (in knm/hr) of (i) the center point and points (ii) 5 cm and (iii) 6 cm from the center? Thanks!
  16. N

    What is instantaneous frequency?

    Instantaneous frequency ω(t), is defined as the time derivative of phase. According to a paper by L.Madel, American Journal of Physics 42, 840 (1974); doi: 10.1119/1.1987876, this is significantly different from the frequencies in the Fourier Spectrum of the signal. However, there is no...
  17. Jalo

    I Photodiode bandwidth: why does power decrease with frequency

    Hi, I'm studying p-i-n photodiode (PD) at the moment and understand that the photodiode's response will depend on the frequency of the light signal going into it. I am struggling however to understand the concept of bandwidth, and why is it that the photocurrent at the PD decreases with higher...
  18. A

    Angular frequency of the small oscillations of a pendulum

    Homework Statement One silly thing may be I am missing for small oscillations of a pendulum the potential energy is -mglcosθ ,for θ=0 is the point of stable equilibrium (e.g minimum potential energy) .Homework Equations Small oscillations angular frequency ω=√(d2Veffect./mdθ2) about stable...
  19. U

    How Do You Calculate the Natural Angular Frequency of a Dual-Spring System?

    Homework Statement The suspension of a modified baby bouncer is modeled by a model spring AP with stiffness k1 and a model damper BP with damping coefficient r. The seat is tethered to the ground, and this tether is modeled by a second model spring PC with stiffness k2. The bouncer is...
  20. O

    Frequency of Modulated Signal: Carrier vs Message

    If a carrier signal is 1000 Hz, and my message signal has a bandwidth of 100 Hz. Is there any change in frequency of the modulated signal? Why is it said that the message signal is now operating between 1000hz +/- 100Hz? I thought the original message signal frequency remains unchanged...
  21. DariusP

    Frequency Doubling: Interaction of 2 Waves Explained

    How can two waves interacting with each other produce a wave with double the frequency? I always thought two waves can only interfere constructively or destructively, hence, increasing or decreasing their amplitude but keeping frequency the same.
  22. Nikhil Rajagopalan

    Standing Wave Fundamental Frequency and Particle Vibration

    For a wave A sin ( kx - ωt) and a wave A sin ( kx + ωt) traveling opposite to each other, on evaluating by applying superposition principle , the resultant displacement function is 2A sin ( kx ) cos (ωt) . For different Node Anti-node configurations we calculate natural frequencies of the...
  23. A

    Clear formula for water penetration by wave frequency

    I want a clear formula for clear water (and salty water) penetration by giving only the radio wave frequency . I searched the web , the formulas on the web are so complicated . Are there any simple formula available for that ?
  24. Drugstore Cowboy

    I Solar spectral intensity per wavelength - frequency

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  25. Alex Katko

    Calculate the natural circular frequency ωn of the system

    Homework Statement Calculate the natural circular frequency ωn of the system shown in the figure. The mass and friction of the pulleys are negligible. The diagram is attached. Homework Equations ωn = (k/m)1/2 The Attempt at a Solution I can see the total mass of the system is 3m. So in the...
  26. DariusP

    Why Do Metals Stop Reflecting Light at Certain Frequencies?

    Hello, I am having a very hard time understanding what is plasma frequency by reading definitions. I know, for example, that metals have a metallic bond and can be analysed like plasma because of an equal distribution of electrons in electron gas and positively charged atoms. I know metals are...
  27. S

    I Poles in Casimir force as function of frequency & mode

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  28. F

    How to calculate natural frequency of timing belt

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  29. astroman707

    Derive the formula for the frequency of a spring

    Homework Statement Two masses m1 and m2 are joined by a spring of spring constant k. Show that the frequency of vibration of these masses along the line connecting them is ω = √[ k(m1 + m2) / (m1*m2) ] (Hint: Center of mass remains at rest.) Homework Equations f = w/2π w = √(k/m) F = -kx a = -...
  30. tworitdash

    What is the attenuation below cut-off frequency for TE10?

    It is not useful to talk about the attenuation below cut-off frequency, but I have this doubt about what happens to the wave below cut off for an electric conductor. As we know if we derive the propagation constant, it becomes imaginary saying that there should not be any wave propagating in the...
  31. M

    Solving Differential Equation with Frequency Response

    Homework Statement The AC response of an inductor can be modeled by the following differential equation: L \frac{di}{dt} + iR = V Find, using frequency response, the current of the system when the applied voltage V is: V = V_0 \sin(\omega t) Homework EquationsThe Attempt at a Solution In...
  32. G

    Radio Frequency Acceleration in Particle Accelerators

    So, I've been really interested in Particle Physics since 6th grade when I did a project on particle accelerators. I understand most of it, except for one thing, the radio frequency cavities which are used for acceleration. I just want to ask, how do the Superconducting Radio Frequency Cavities...
  33. CDL

    Mean Frequency and Frequency Spread of a Laser Pulse

    Homework Statement Laser probes are being used to examine the states of atoms and molecules at high temporal resolution. A laser operating at a wavelength of 400 nm produces a 1 femtosecond pulse. Compute the mean frequency and frequency spread, ∆ν, of this laser pulse. Homework Equations c =...
  34. M

    Does the size of an antenna matter?

    Hello. I have a very small antenna and I was wondering if it can receive and/or transmit low frequency signals (or if it can only receive/transmit high frequencies). Likewise, do I need a very large antenna to receive/transmit low frequencies? I've read somewhere on the internet that the...
  35. M

    Frequency of Differently Coloured Light

    We know that light of a specific colour has a specific frequency. Suppose we have a torch emitting white light, and we place a, say, red cellophane paper, in front of it. Now we would have red light. So does this mean the new beam we get has a new frequency? How?
  36. S

    B Frequnncy and 1/t, I don't really understand

    if freqeuncy is 1/t then if i was given t, then f is the reciprocal of t right? f=1/t t=20s f=1/20 f=0.05Hz right? another thing, if 1 is the number of cycles per second, isn't it also a variable? so if i know the freqeuncy which is 0.05 Hz, and the T is 20s, then the number of cycles is...
  37. Laserray

    T Section Lowpass LC Filter Frequency Formula

    I have been trying to find out how the cutoff equation for the T section LC Lowpass filter is derived. I remember from college that f=1/(2pi√(LC)) for an LC circuit. But, with the T section, the cutoff frequency is given by f=1/(pi√(LC)), with L being the sum of the two inductors. My math has...
  38. Y

    Angular frequency of an ammonia molecule

    Hello 1. Homework Statement The dipole moment of an ammonia molecule is ##d_0=5*10^{-30} C.m##.If we apply a static electric field of ##\mathcal { E }=1*10^{6 }V*m^{-1}## to an ammonia molecule initially in the state ## |ψG⟩## where the nitrogen molecule is considered to be on the left,we make...
  39. K

    Lowering frequency in transformers

    A transforming winding is like a short circuit.. except there is inductance caused by alternating current and the frequency that produce some resistance. What would happen if the frequency is lowered.. would there be a threshold value that would begin to make it as short circuit? like 30 Hz...
  40. G

    Calculate Frequency of Flat Spring Steel for Reed Valves in a Pulse Jet Engine

    I need to calculate the frequency of a flat spring. I need to make reed valves for a pulse jet engine. I read online to use Hooks's Law but this is not working. F = force. x = the amount spring moves. k = spring constant. I have a flat spring made of .010" spring steel. Spring is .375"...
  41. YMMMA

    What are the frequency and speed of a photon after scattering

    Homework Statement Photons incident upon free electrons that are essen- tially at rest are scattered by the electrons. As a consequence, the electrons gain kinetic energy. How do the frequency and speed of the photons present after the scattering compare to those present before the scattering...
  42. SuchBants

    Finding the max frequency of a driven oscillator

    So I've derived the equation for the amplitude of a driven oscillator as: \huge A=\frac{F}{m\sqrt{(\omega_{0}^{2}-\omega_{d}^{2})^{2}+4\gamma^{2}\omega_{d}^{2}}} Which is what my lecturer has written. Then taking the derivative and setting it to 0 to get the turning point. He makes this leap...
  43. J

    Small oscillation frequency of rod and disk pendulum

    Homework Statement Consider a rod of length ##L## and mass ##M## attached on one end to the ceiling and on the other end to the edge of a disk of radius ##r## and mass ##m##. This system is slightly moved away from the vertical and let go. Let ##\theta## be the angle the pendulum makes with the...
  44. Exidor

    Trouble with high frequency astable multivibrator

    I am having trouble getting an astable multivibrator to oscillate higher than 480 KHz. I added a "baker clamp" which gave some improvement, but didn't get me to the target frequency of 816.5 KHz. I am on an iPad and can't post a schematic. I use 2sc6082-1e transistors and bat41 diodes for the...
  45. YMMMA

    Compare the speed and frequency of a wave in a thick rope

    Homework Statement In the attached file. Homework Equations No equations needed. The Attempt at a Solution I answered it B. Not sure,though. If it is a thick rope the frequency decreses; therefore, the speed decreases.
  46. C

    I Do gravitons have frequency, like photons?

    Something I've been thinking about lately. If so, how'd we detect high frequency gravitons? I have Bachelors in physics so you may get a little technical ;)
  47. Helloworld

    Frequency and wavelength of a wave on a vertical rope

    Homework Statement A long, heavy rope hangs straight down from a high balcony on an apartment building. The lower end of the rope hangs about 1.0 m above the ground. If you grab onto the lower end and waggle it back and forth with constant frequency f, a wave travels up the rope. What would...
  48. mertcan

    Can Maxwell's Method Be Used for High Frequency Circuit Calculations?

    Hi, initially I have seen that when circuits are exposed to high frequency kirchhoff laws become invalid. According to my search I can not find any derived circuit equations for that case, instead computational electromagnetism method is suggested using maxwell. Is it the only way to make...
  49. B

    Highest Frequency emitted by bremsstrahlung

    Homework Statement Electrons are accelerated in a television tube through a potential difference of 8.5 kV. What is the highest frequency of the electromagnetic waves emitted when these electrons strike the screen of the tube? Homework Equations λ = c/f E (of the electron) = V*e E (of the...
  50. bob012345

    Very Low Frequency EM Waves (now: Magnetic Launcher)

    Is it possible to make very low frequency EM waves, say 10 KHz, without an antenna the size of Texas? Something more human sized? Thanks.
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