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. John mcgarvie

    Is it possible to transmit frequency of a solid object?

    Hello I'm asking if the resonate frequency of a solid object say a rock. Can be transmitted/guided to change the natural frequency of an object say a rock with a different frequency. And I hope this is a proper question.
  2. gmalcolm77

    I Photon Frequency: Can a Photon Change Color?

    Can a photon ever change frequency? What I mean is, can say a photon of red light ever become a photon of green or yellow light?
  3. entropy1

    B Oscillations in a driven spring

    If I have a spring with resonance frequency fres and I drive it with frequency fdrive, the spring will oscillate in a superposition of two frequencies, right? Which frequencies are they?
  4. G

    Synchro Signal Frequency changes

    Hi there! i have a question regarding signal and hope someone can help me out. Currently, i have a system that outputs synchro signal to other system. Apparently when the cables are connected to the system, the frequency of the synchro signal changes. From around 400KHz, it became around 1.2KHz...
  5. T

    Pulse repetition frequency ultrasound confusion

    Homework Statement Q:[/B]An ultrasound department seeks your advice regarding scans they perform to visualise and confirm foetal heart beating. They wish to know what imaging frame rate should be set in order to visualise the heart movement reliably but achieve the maximum possible reduction in...
  6. M

    Sources of Error in a Speed of Sound Experiment

    Homework Statement Determine sources of error which could have affected the results. Some background information: The lab consisted of playing a tone generated by a tone generator above a standing open-closed tube which had water in it. The first harmonic was measured through a computer system...
  7. S

    I Is there a frequency cutoff for Debye theory of capillary waves?

    I calculated the energy density of capillary waves with Debye method (pretty much Debye model in 2D), and I assumed there is a frequency cutoff for capillary waves as well. However, when I checked my work with solution I was quite surprised that the solution suggests there is no such a cuttoff...
  8. M

    MHB Calculate the rotational frequency in r/s and the diameter of the drive pulley

    a belt is driven by a pulley at 33m/s the pulley rotates at 750 r/min. calculate: (a) the rotational frequency in r/s (b) the diameter of the drive pulley
  9. T

    Wall thickness vs frequency.... sound isolation

    When sound hits a wall,part of it gets reflected and part of it gets transmitted due to acoustic impedance difference between solid and air. My problem,and point of this question is that having material or gas impedance number is completely useless unless we know the frequency and wall...
  10. J

    Ripple frequency of three phase half bridge converter

    Homework Statement Homework Equations Three phase half controlled bridge rectifier can have 3 pules at output or 6 pulses depending on firing angle. The Attempt at a Solution Ripple frequency is m times the input frequency where m is number of pulses. It can be 3 or 6. So why have they...
  11. B

    The difference between angular frequency and frequency?

    I looked up and read the definitions in several different books, but still don't get it. Is someone willing to explain it to me on a really simple level?
  12. Acookook

    Calcultating circular frequency and phase on a spring

    Am I trying to solve a simple equation, but get stuck at the basic. I have have a spring with a cube attached to it (1kg). When I pull it with 5N, the spring extends to 50mm =amplitude, (Hooks law) the koefitient is 120. The determined absortion coeffitient is 0,2^-1s. I tried to get the...
  13. Perodamh

    What is the resonant frequency and peak current drawn

    Homework Statement A series RLC current having a resistance of 40ohms and inductance of 400mH and a capacitance of 300microfarad is energized from 50Hz, 200V A.C supply. Find i) Resonance Frequency of the circuit ii) Peak current drawn by the circuit at 50Hz iii) Peak current drawn by the...
  14. S

    Frequency of Wave on a Guitar String HW

    Homework Statement When a guitar string is stretched to have a tension T, it produces a frequency f. You change the tension by a very small amount ∆T . Show that the new frequency of the guitar string is fnew = f ( 1 + (delta T)/2T) For example, a guitar string has tension T = 10N and...
  15. P

    Longer pendulum, does frequency need to be increased or

    A motor drives a pendulum at its natural frequency and keeps it swinging at a constant rate. If this motor uses a longer pendulum, does a frequency need to be increased or decreased? I'm assuming that the question is asking whether or not the frequency that the motor drives a pendulum needs to...
  16. W

    Q-Switching Frequency for Acousto-Optic Modulator & 980nm Laser

    Homework Statement An acousto-optic modulator is used to Q-switch a laser with ##\lambda = 980##nm. The angle of deflection is ##\theta = 0.1## degrees, the speed of sound in quartz is 3700m/s and it has refractive index of 1.5. What is the maximum Q switch rate? I'm not exactly sure what I'm...
  17. D

    Engineering Calculating the effective value and frequency of AC Circuit

    Homework Statement For AC Circuit shown in the picture, ##C=60nF##, ##L=100uH##, ##X_3=-100Ω##, ##Z_2=50Ω## and ##Φ_2=\frac {\pi}{6}##. When the switch is closed the ammeter shows a current ##I_1=0.6A## and the voltmeter shows ##U_l=60V##. The measuring instruments mentioned are ideal...
  18. J

    Asynchronous Counter 4-bit Output Frequency

    Homework Statement [/B]Y is output of rightmost flip flop. Q Homework Equations Drawing Timing Diagram. F(o/p) = F(clock)/(number of stages in output) The Attempt at a Solution The last flip flop has positive triggering clock. The moment Flip Flop output becomes 110X with MSB being rightmost...
  19. K

    Calculate the time out of sample points with set frequency

    Hi all, at the moment I am doing my Master Thesis and have the following problem. I am trying to measure Data and asign it a proper timestamp. My problem is, that the data is coming in bursts and the timestamps I assign with the software are wrong. The controller I am using for monitoring the...
  20. T

    Can a radio frequency be lowered by a passive circuit?

    Is it possible to design an unpowered antenna, (possibly some kind of RLC circuit) which will receive a radio wave at a particular frequency and then re-emit it at a lower frequency?
  21. B

    What Is the Frequency of Radiation Emitted by a Constantly Accelerating Charge?

    When a charge is accelerated it brakes because it emits radiation. If a carge is accelerated with costant acceleration and the traiectory is a line what is the frequency of the emitted radiation? (I think 0Hz but i am not sure)
  22. D

    Calculating the resonant frequency of a gas cylinder

    I would like to make a bell out of a used compressed gas cylinder, but I would like to tune it to a specific note or frequency, e.g. A (440Hz). Can someone help with a formula to calculate this so I can cut it precisely?
  23. R

    What is the Frequency of Emitted Radiation from a Moving Hydrogen Atom?

    Consider an excited hydrogen atom in state n moving with a velocity v<c. it emits a photon in the direction of its motion and changes its state to a lower state m. Find the frequency of emitted radiation in terms of frequency fo if the atom were at rest. My approach: I tried by taking recoil...
  24. Pushoam

    Frequency of a proton moving in a circular orbit

    Homework Statement Homework EquationsThe Attempt at a Solution [/B]Assuming that the relation ## v = \omega r ## is valid in relativistic calculation. As the speed is greater for higher kinetic energy, ## \omega_2 ## is greater. This is shown by only (d). So, I think (d) should...
  25. Pushoam

    Engineering LCR circuit, calculating R when frequency width is given

    Homework Statement Homework EquationsThe Attempt at a Solution LCR circuit, calculating R when frequency width is given Applying Kirchoff Voltage Loop Law, ## V_A – V_B + V_B - V_C + V_C – V_A = 0 ## ...(2) ## V_A – V_B ## is potential drop across inductor. Since current is flowing...
  26. B

    Complex Frequency Derivation-Magically Appearing "j"s

    Homework Statement From Hayt "Engineering Circuit Analysis". I'm just wondering how the imaginary "j" multipliers appeared. Homework EquationsThe Attempt at a Solution
  27. S

    Device with which I can measure the frequency of light

    Does anybody know where i can buy a device with which i can measure the frequency of light from various sources such as bulb light?
  28. Pushoam

    The effect on a photocurrent of reducing the frequency of photons

    Homework Statement Homework EquationsThe Attempt at a Solution As frequency is decreased to threshold, no. of emitted electrons will remain same, but their maximum kinetic energy will decrease. So, the current should decrease slowly. For frequency less than the threshold frequency, no...
  29. I

    Natural Frequency of a Foam Block?

    Hello everyone, Looking for some help on how to go about finding the natural frequency of a block of foam. The foam has a density of 0.37 lbs./ft^3 and is 48"x48"x8" (LxWxD) in size. Weight is approximately 5.4 lbs. I have been digging around the internet for quite some time with no such luck...
  30. AbigailG

    Find an Expression for the Frequency - Pendulum

    Homework Statement [/B] A solid sphere of mass M and radius R is suspended from a thin rod. The sphere can swing back and forth at the bottom of the rod. Find an expression for the frequency of small angle oscillations.Homework Equations f = 1/2(pi) sqrt(MgR/I) I for a solid sphere 2/5MR^2The...
  31. N

    Natural Frequency of Elastic Pipe with Different Pressures

    Hi, I have a 3mm diameter flexible silicone tube with wall diameter of 0.5mm. If this tube is filled with water at different pressures, how does the internal pressure present itself during modal testing (either shaker or impact testing). The tube lies on rigid table so it is completely...
  32. J

    Travelling towards a Canyon Wall: Calculating Beat Frequency

    Homework Statement 1. On a long trip that you take to forget for a while about physics, you find yourself driving directly towards a canyon wall. You’ve previously noticed that your car horn has a frequency of 440 Hz. You glance at the speedometer and notice you’re moving at 30 km/h...
  33. Feodalherren

    First natural frequency for bending, axial and torsion modes

    Homework Statement We have a rod of length L fixed to a rigid support. At the end of the rod there is a mass, m. Assume that the rod has no mass. Find the first natural frequency for the bending, axial and torsion modes. Homework EquationsThe Attempt at a Solution So I'm reviewing some stuff...
  34. G

    Generator size vs frequency question

    Hi folks , a simple question, is it true that generators are like transformers in regard to the frequency of the AC being generated versus the size of the device for given amount of power transfer? We know that transformers can have smaller cores with fewer turns if the frequency of the AC is...
  35. D

    What Is the Fundamental Frequency of a Modified Stretched Wire?

    Homework Statement A stretched wire vibrates in its first normal mode at a frequency of 369Hz. What would be the fundamental frequency if the wire were one third as long, its diameter were tripled, and its tension were increased two-fold? Homework Equations f = 1/2L * squareroot(Ft/u) The...
  36. jim mcnamara

    Volcanic super-eruption frequency revised to shorter time

    'The global magnitude-frequency relationship for large explosive volcanic eruptions' by J. Rougier, S. Sparks, K. Cashman, and S. Brown, in Earth and Planetary Science Letters. (If someone can post a link to at least the abstract that would help) Popular science version...
  37. bahtiyar

    What factors affect the frequency of harmonics in a soda bottle?

    I saw a question "If you blow across the open end of a soda bottle and produce a tone of 250 Hz, what will be the frequency of the next harmonic heard if you blow much harder?" the answer is 750 Hz but I'm curious about "if you blow much harder" part, is it really depends on how much harder...
  38. DeathbyGreen

    I Finding Harmonic Relationships Between Frequencies in Experimental Data

    I'm trying to relate some different frequencies together in an experiment. Say I have 3 different frequencies, \omega_1,\omega_2, \omega_3. Omega 3 is the large envelope, and the other two must fit inside of it, and so they are integer multiples of each other. Is there some way to express...
  39. EastWindBreaks

    Why am I not getting the correct natural frequency?

    Homework Statement To find the natural frequency of a uniform cantilever beam, the area moment of inertia, cross-sectional area and density are not given, everything else is given by the lab, our group got a theoretical natural frequency( it might be angular frequency) of 27.44 Hz from lab's...
  40. D

    I How does one make an Amplitude vs. Frequency plot?

    I am working on homework for a physics lab course and I am asked to write a python function which will produce an amplitude v.s frequency plot. In a previous problem I wrote a function which simulates data from a sine wave in the form of a time series; the new function should be able to take...
  41. F

    I How does a harmonic oscillator model have the same frequency

    I'm currently studying IR but my mind is having trouble tying everything together. While I see that vibrational frequency is determined really by just reduced mass, I can see from the equation that vib equation is the same throughout energy levels and so does energy (bc that basically depends...
  42. T

    Maximum frequency if there is to be one diffraction order

    Homework Statement A naval towed-array sonar comprises a line of ##80## transducers, equally spaced over a total length of ##120 m##, that is towed behind a ship so that it lies in a straight line just below the surface of the water. An adjustable phase delay can be introduced electronically...
  43. W

    Self-Induced Emf and Angular Frequency

    The context is an ac circuit with only one element - the inductor. My textbook says that the self-induced emf increases with increasing angular frequency, but I'm having trouble seeing this mathematically. If self-induced emf = ε = -L(dI/dt) and L = X/ω, then emf and ω are inversely related...
  44. R

    Counting clicks (signals) at a radio frequency receoved by a shortwave radio

    Hello. I'm an English language teacher researching the details of a class project; I use projects to develop language skills. I have a background in mechanical engineering but know little to nothing of electrical engineering, hence this post. Questions for members of this forum: Electrical...
  45. nothing909

    INA Frequency Response: Gain, Circuit & Open Loop Explained

    1. QUESTION i'm dealing with a 3op instrumentation amplifier. say i have a circuit gain of 100 and i have an INA with a gain bandwidth product of 2MHz. the two buffer differential amplifiers are at 100k the open loop gain is then 2MHz/100k = 20 this frequency of 100k is going to effect the...
  46. C

    The equation to find the frequency of a bouncing ball

    [Mentors' note: No template because this thread was moved from the General Physics forum] Ok so first of all believe me i would not make a new post if i found the answer anywhere online but i i couldn't find it. Right now i am doing an experiment to find the frequency of a bouncing ping-pong...
  47. C

    Measuring the Speed of Sound: Examining the Frequency of Clicks

    Homework Statement This is a problem from the Cambridge Natural Science Admissions Assesment. A student carries out an experiment to measure the speed of sound. A loudspeaker that emits sound in all directions is placed between two buildings that are 128 m apart as shown. The student and...
  48. mheslep

    Fuel rod leak (failure) frequency

    After reviewing some old threads (e.g. here), anecdotally I see that fuel rods do suffer failures on occasion, but it appears not very often, as is intended. My question is, why not more frequently? Given a power reactor neutron flux of 1014 n/cm2-s, it seems like every atom in the cladding...
  49. B

    How Do You Calculate the Normalized Frequency for a Multimode Fiber?

    Hi, I'm having trouble calculating the normalized frequency for a multimode fiber. Here's the formula: V=(2π/λ)⋅a⋅√(n12-n22) where λ=900 nm, a=200μm, n1=1.460, n2=1.455 Here's how I plug in the numbers: V=(2π/(900*10-9))⋅(200*10-6)⋅√(1.4602-1.4552)=167This is an easy calculation I know...
  50. M

    Capacitors in Hybrid-pi Model and Frequency Response

    This is what I have and I was wondering where C2 might go if I make apply the hybrid pi model on this circuit. I know that all the DC Voltages should be shorted if I were to make use of an equivalent circuit, so that in the hybrid pi model R1 should be in the input and R3 in the output. But what...
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