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. S

    Resonance Frequency Homework: Find Frequency w/Given Spring & Mass

    Homework Statement A certain spring elongates 9:0mm when it is suspended vertically and a block of mass M is hung on it. If driven by a force of variable frequency, at what frequency would resonance be obtained?a. is 0:088 rad/s b. is 200 rad/s c. is 33 rad/s d. is 1140 rad/s e. cannot be...
  2. A

    Highest frequency of sound waves in a thin aluminium rod

    Homework Statement Estimate the highest possible frequency (in Hertz) and the smallest possible wavelength, of a sound wave in aluminium due to the discrete atomic structure of this material. The mass density, Young's modulus, and atomic weight of aluminium are 2.7x103kg m-3, 6x1010 N m-2, and...
  3. J

    Highest possible AC frequency possible today?

    What is the highest possible AC frequency being able to be generated. I don't care if this is usable in a circuit but as long as it can be physically made, what is the highest AC frequency possible? I've heard 70GHz was the max using an amplifier.
  4. A

    Inductive Circuit and Frequency

    Homework Statement A resistor and a capacitor are connected in series to a variable frequency supply. A voltmerter is connected across the inductor and another across the resistor. The supply voltage is kept constant as frequency of supply is increased. State and explain the changes in the...
  5. G

    Finding gravitron rotational frequency

    Homework Statement In an old-fashioned amusement park ride, passengers stand inside a 3.0-m-tall, 5.0-m-diameter hollow steel cylinder with their backs against the wall. The cylinder begins to rotate about a vertical axis. Then the floor on which the passengers are standing suddenly drops away...
  6. S

    Sound waves frequency (Hankel functions)

    Homework Statement Let's study harmonic sound waves with frequency ##\omega ##, that is emitted by a long wire. Let's approximate the earth, above which the wire is, with an infinite rigid plate. If the space wasn't limited by the earth, than the velocity potential of the source would be ##\Phi...
  7. L

    Oscillating Hydrofoil Frequency

    Homework Statement Evening, As part of a project we are building a pico oscillating hydroelectricity generation system. Our system is based on the flow of a river providing lift onto a hydrofoil, which is then connected to a flywheel via a mechanism, the energy and rotational speed in the...
  8. J

    Setting up an LRC series circuit with coupled coils

    Homework Statement I have been trying to set up an LRC series circuit where in place of an inductor we have a pair of coupled coils. My aim is to determine the resonant frequency in the circuit when the voltage across the resistor or the current in the circuit is at a maximum. I am using a...
  9. W

    Frequency of Moving Sound Source

    Homework Statement A sound source has frequency 1000Hz and moves at velocity v along a straight line. A person stands a perpendicular distance d away from the line. At time t=0 the source is at its distance of closest approach to the listener. Express the frequency as heard by the listener as a...
  10. J

    Frequency modulated laser - transmission of voice

    If I modulated a laser frequency with voice, would a photo cell be capable of receiving that information?
  11. G

    High Frequency signal with fast risetime, its bandwidth

    Hi, I am new to world of electronics and to high frequency Domain. But I am working on a design where I have a coax of 30cm length. I have used an external oscillator to generate 7GHz fast falling pulse. I am using a Controller to control the oscillator. Now I have a pulse of about 350ns...
  12. Electro_vass

    How Does Frequency Affect a Circuit with Capacitors and Inductors?

    Hi, Im quite new to frequency and how it effects a circuit with both capacitors and inductor. I have created a simple circuit in Multisim and run an AC-analysis. Pictures of both circuit and analysis is attachments. What is happening here. And arent the circuit also depending on the time...
  13. W

    Frequency of sound waves from vibrating wire

    Homework Statement The wire has mass 250g and is tied down at both ends. It has a length of 12.50m and a fundamental frequency of 25.0 Hz. It has linear mass density. Sound travels at 344m/s in air. Calculate the frequency of the sound waves produced when the wire vibrates at its fifth...
  14. M

    Photon energy and calculating frequency

    Hello guys, I am having a bit of trouble with some homework So I am told that a photon in a light beam has an energy og 2,12 eV. First i have to calculate the energy of it in joules, and since 1 eV is 1,60*10^-19 Joules 2,12 eV in joules is just 2,12*1,60*10^-19 = 3.392*10−19 J i got that. Then...
  15. M

    What exactly is a threshold frequency?

    For example, when you have a photon interacting with a bound electron, there is a work function relating the minimum energy photon capable of interaction (given by hf). My question is, what exactly is going on in this situation if the work function is exactly equivalent or less than the energy...
  16. A

    Solving the Slinky Wave Problem: HELP!

    Homework Statement A slinky with natural length of 3.00 meters, mass of 0.750 kg, and spring constant 18.0 N/m is stretched out along a floor, each end held by a seated person. The final length is 8.2 m. One end is plucked sending a transverse pulse. Find the pulse's travel time there AND back...
  17. T

    Satellite Frequency: Revs/Day Calculation Homework

    Homework Statement A satellite in a orbit has a period of 15 hours. What is its frequency in revolutions per day?
  18. C

    Determining a specific frequency to make the ball bounce

    So, here's the set-up: A small stereo speaker is connected to a function generator. A concave lens, bearing a ball is place over the speaker. Now, the frequency is slowly increased in the function generator. My question is, Will the ball really bounce at a certain frequency? Because I am not...
  19. Paradox101

    LASER Operating At A Certain Frequency

    Q. A LASER is operating at a frequency f = 6.1*10^14 Hz. A)Calculate the momentum of the photon emitted by the laser. B)A helium atom flies towards the laser at a speed of v = 3.5 m/s.During one laser pulse the gold atom absorbs on average 5 photons.Find the speed the helium atom after one laser...
  20. J

    Proving the Frequency Response of Notch Filter F(s)

    Homework Statement Question is when F(s) = ## \frac {(s)^2+2*ζa*Wn*s+(Wn)^2)} {(s)^2+2*ζb*Wn*s+(Wn)^2)} \ ## prove that ## \ {|F(iw)|}^2 \ ## = 1 - ## \frac {4(ζb^2-ζa^2) \tilde w} {(1-\tilde w)^2+4ζb^2 \tilde w} \ ## when ## \tilde w \ ## = ## (\frac {w} {Wn} )^2 \ ## Homework Equations...
  21. arpon

    What happens when the observer hears sounds from a super sonic source?

    As we know, when the observer is moving away from the source, then the apparent frequency is, ##f_{observer} = f_{source} (\frac{v_{sound} - v_{observer}}{v_{sound}})## But, if ##v_{observer} > v_{sound}## , ##f_{observer}## becomes negative.
  22. A

    Op amp and 3-db frequency problem

    Homework Statement An inverting amplifier with the DC gain of -9 (V/V) is built with an op amp having its DC gain of 105 and corner frequency of 30 rad/s. ▪ Determine the 3-dB frequency of the inverting amplifier. ▪ Sketch the magnitude Bode plot of the voltage transfer function of the...
  23. R

    Forced Frequency Homework: Which of These Acts as a Force?

    Homework Statement Which of the following is a forced frequency acting on the oscillations? I. A pendulum skims the surface of a pool of water at the lowest point of motion. II. To keep a bell ringing, a bell ringer pulls on a bell rope. III. A singer shatters a glass. Homework EquationsThe...
  24. W

    Clockwise rotation of the reflection coefficient w/ frequency

    It is always considered that the evolution of the input reflection coefficient, ρ, of a LTI causal passive system with frequency, f, always presents a local clockwise rotation when plotted in cartesian axes (Re(ρ), Im(ρ)), e.g. in a Smith chart, as shown in the attached figure. It must...
  25. W

    Rotation of the reflection coeff. at Smith Chart w/ frequency

    It is always considered that the evolution of the input reflection coefficient, ρ, of a LTI causal passive system with frequency, f, always presents a local clockwise rotation when plotted in cartesian axes (Re(ρ), Im(ρ)), e.g. in a Smith chart, as shown in the attached figure. It must...
  26. A

    How to find supply frequency of an AC circuit

    Homework Statement [/B] Parallel circuit consists of 100ohm resistor with 0.4A current, a 0.47uf capacitor with 0.177A current. Both connected across an AC supply, determineHomework Equations [/B] The supply voltage The supply frequency Current drawn from supply Power factor of the circuit The...
  27. D

    Exploring Doppler Shift: How Motion Affects Wave Frequency

    Hello to everyone! First I would like to go through one simple example: We have two bodies. One is wave source, other is wave receiver. In this example they are positioned like this: (source) O=====> (receiver) O=====> Distance between them is always 1000 m. Let's say that the waves are...
  28. N

    Frequency Question -- 24 VAC, 60 Hz versus 24 VAC, 20 Hz

    Suppose that I have two sources: 1. 24 VAC, 60 Hz and 2. 24 VAC, 20 Hz Then I will use it to power into certain load (maybe we can assume a purely resistive load to simplify the question). What would be the effect of those sources to the load? How about the current flowing? I think (1) and (2)...
  29. pitbull

    Optimizing the Pivot Point for a Uniform Bar's Frequency of Oscillation

    Homework Statement Given a uniform bar of length L, which point should you hang it from (between 0 and L) so that you get maximum frequency for small oscillations? Homework Equations ... The Attempt at a Solution It seems like a basic problem, but I don´t know how to start. Could you guys...
  30. K

    What is the frequency of the harmonic potential?

    Hi there, I am reading an introduction on trapping atoms in space with magnetic potential. The article said the lab usually use a harmonic potential to trap the atoms and the potentials is in the form ##\dfrac{m}{2}(\omega_x^2x^2 + \omega_y^2y^2 + \omega_z^2z^2)## and ##\omega_{x,y,z}## has...
  31. A

    How Does Input Capacitance Influence IRF530 MOSFET's Maximum Input Frequency?

    Hi everyone, I am using IRF530 in a half h bridge DC motor driver. The MOSFET is behaving erratically if the PWM frequency is increased above 20 KHz. I checked the datasheet thoroughly but could not find any thing related to maximum operating frequency. Is input capacitance related in any way...
  32. mostwantedmani

    Increase the frequency of AC current

    How to increase or decrease the frequency of AC current linearly? Suggest me some ideas
  33. ranju

    Infinite Voltage & Frequency in Power Grids: What's the Reason?

    I have got to know that the voltage and frequency of the supply in the power grids is kept as infinity.>! But what is the reason behind it..?? Well for the voltage to be infinity , I have studied that losses are inversely proportional to square of supply voltage ..so higher is the voltage ...
  34. P

    Sound waves in a closed pipe Problem

    Homework Statement Before I write the question you should know that my maths is all correct in my solution but I must have used the formulas incorrectly (or used the wrong formulas). I can't pinpoint where I've gone wrong or if I have left a formula out (I'm a teacher solving this question for...
  35. Z

    Wave Amplification & Frequency Transformation

    I understand the concepts behind the terms in the title; however, I have a question about how to transform the wave energy itself. I'm working on a science fair project that involves transforming sound energy into electrical energy--I understand this is not a very reasonable method of harvesting...
  36. Mickey Tee

    Changing pitch in frequency ratio?

    Homework Statement Homework Equations v=fΛ v=√(T/μ) The Attempt at a Solution I know I'm supposed to make an attempt, but I can make heads nor tails of this. Are they changed in a constant ratioo? Does the tension come into play? The answer given is 0.16m
  37. M

    Gravity Waves: Frequency & Understanding Needed

    I got one solution for an simple ode that involving gravity wave frequency . Before going further I have to understand more about gravity wave . So I need your help guys ...
  38. E

    How Do You Design a BJT Amplifier with Specific -3dB Points at 10Hz and 10kHz?

    I would like to know how to design an amplifier similar to the attached circuit with set -3db points, the lower on the order of 10Hz, and the higher on the order of 10kHz. I have designed amplifiers to work with a set gain, but have not dealt with frequency response before. I designed an amp...
  39. E

    Find total length of cylinder (springs, natural frequency)

    Homework Statement A simple pressure relief device is shown in Figure Q6.1 below. It consists of a piston of mass 0.5 kg and thickness 3 cm sliding without leakage or friction into a cylinder of diameter 5 cm. The bottom section of the cylinder can be exposed to a varying source of pressure...
  40. Lamdbaenergy

    Planck's law (wavelength, frequency, angle?)

    So I was just looking around today and stumbled upon something called Planck's law. I saw an equation and quite few more of them that looked like this, I'm familiar with all of the other variables and constants already, but don't get the E (hv/kT) part, yet. Is E the energy of the photons you...
  41. D

    Solve Two Tasks with One DC Signal: Solid State Switch Circuit

    My goal is to use a single signal to do two things at the same time...when DC signal is applied turn transistor1 off and turn transistor2 on. Then when signal is not applied transistor1 returns to on and transistor2 returns to off. Frequency will be no more than 60Hz. What would this circuit...
  42. R

    How higher frequency EM waves become more dangerous

    How high frequency makes waves dangerous for us.also does all em waves have same speed of light?
  43. marasciallo

    Frequency response function of periodic-stiffness model of system

    Hi, I'm analyzing a 3 dof undamped system with discrete springs and masses. Three of the springs have time-dependent stiffness, following periodic law (with period T), they are modulated at the same frequency but with a phase difference of 120 deg one from the other. So this is my system: (M *...
  44. ranju

    Transformer Frequency: No Relative Motion Explained

    We know that frequency of induced emf in secondary coil remains same as frequency of applied voltage in primary coil and I have read that its reason is " there is no relative motion between the coils..". Actually I am not getting the reason , maybe some fact or concept has slipped from my mind...
  45. A

    Doppler effect - Apparent change in frequency or wavelength?

    Hello, I've been thinking about what exactly is the doppler effect and I'm not sure I understand it because I thought it meant a change in frequency due to relative motion while at the same time its defined in terms of changing wavelength such as in red shift or blue shift. Case 1 The...
  46. S

    Collision frequency unit conversion

    hi all I have a question about unit for collision frequency. The unit is collision per second and is it same with hertz? Thanks
  47. N

    Fourier transform power dependent on frequency

    Homework Statement this is something i noticed doing homework rather than homework itself. I plot fft output from different frequency signals, i am not sure why power changes with increasing frequency? Homework Equations if i take (with MATLAB notation): time = 0:0.01:10 y =...
  48. E

    Find the Frequency Spectrum of an optical communication link

    Homework Statement 2. Homework Equations 10 Log[10](g/mW)= GdBw The Attempt at a Solution I have attached a document of my approach to this question. I would like to know if my approach is correct? Thank you for your assistance
  49. A.T.

    LED flicker from utility frequency

    Why do some LED bulbs show clear utility frequency flicker, while others don't? Is it there, but not visible for the weaker lamps because of less amplitude? Is the diffuse bulb coating fluorescent and smooths the flicker away? Here a comparison of some IKEA LEDARE models, slowed down by factor...
  50. LaLaLina

    Frequency of Oscillation, with mass and k value given

    Homework Statement A mass m = 2.0 kg is attached to a spring having a force constant k = 990 N/m as in the figure. The mass is displaced from its equilibrium position and released. Its frequency of oscillation (in Hz) is approximately _____ . [/B] Homework Equations...
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