Frequencies Definition and 412 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. J

    What does Q have to do with frequencies?

    Could someone explain why Quality factor, which as I understand it, is 2pi *(maximum energy stored/energy dissipated per cycle) is related to the resonant frequency/bandwidth? I don't understand the connection between the two concepts. Thanks, John
  2. T

    Let's Talk Frequencies: Can Faster Freq Carry More Data?

    Is a faster frequency capable of carrying more data than a lower frequency? i would say yes because the period is shorter in a faster frequency so you can modulate more data (if amplitude modulation). Does more power get used if the frequency is faster but amplitude is the same? These...
  3. N

    Engineering Resonant frequencies of simple RLC circuit

    I need to find the resonant frequency of the circuit shown in the diagram. http://img216.imageshack.us/img216/1750/gdmn.jpg The loop has a value of 1H, the capacitor has a value of 0.2F and the resistor has a value of 10 ohm. My initial approach has been to try and find the total...
  4. D

    Full range speaker not able to deliver all frequencies with perfection.

    Why is it that a full range speaker is not able to deliver all frequencies at once with perfection as compared to the standard tweeder, midrange, woofer and optionally subwoofer arrangement?
  5. T

    What range of frequencies can be generated by blood flow

    hi i was trying to prepare for a project based on passive sensing of sound waves By using natural sound created naturally by blood flow may be turbulence flow of blood in blood vessels So i want to know how to calculate the frequency ranges which can be generated in the human body
  6. K

    Half Power frequencies for a parallel RLC circuit

    hello! I was in the lab doing the experiment of resonance frequency by plotting the graph of current vs frequency for a parallel RLC circuit. In this experiment i have also to find the Q factor and the bandwidth. The resonance frequency corresponds to the frequency with minimum intensity. Now...
  7. J

    High frequencies and capacitor plates

    Hello, I was wondering at high frequencies, does current literally go through the capacitor plates; from one side to the other? Or is it simply due to charges being stored on the plates, that once the polarity of the circuit has changed, the charges on the plate that has been stored from...
  8. D

    Resonant Frequencies of Coaxial Cylinders

    Does anyone know of a formula for determining the various resonant frequencies of 2 coaxial cylinders with radius a and b and height h? Thanks.
  9. F

    Re-create missing negative frequencies?

    I am being given complex frequency domain data from a measuring instrument. The data does not include negative frequencies. I have some existing software to process this data, but that software currently expects the spectrum data to also include negative frequencies. I want to continue using...
  10. A

    Does Biot-Savart law apply at high frequencies?

    The Biot-Savart law for calculating magnetic fields due to a current is presented in my freshman physics book as a general way of getting B from I. But there's no time delay implied by the integral. Can I just manually throw the time delay into the integral? For instance, to numerically...
  11. M

    Carrying Multiple Frequencies On A Single Copper Cable

    how can a single copper cable carry all the different frequencies and prevent them from interfering with each other and destroying data? (I posted this question in the physics forums because it has to do with waves and frequencies)
  12. S

    Simulink: Understanding Time Steps and Sampling Frequencies

    Hi, I have a project due that has to be done in Simulink. I am somewhat familiar with Simulink, but some things don't make sense to me. First off, What determines the time step between each iteration? eg. when you have a clock in the model, what determines the change in time from one...
  13. M

    How Do Bats Hear High Frequencies?

    Homework Statement Why can animals such as bats, that have tiny, light-weight ear parts, hear sounds with much higher frequencies than humans can hear? Homework Equations written response The Attempt at a Solution Waves with low frequencies are smaller than those with high, so...
  14. A

    Change in Amplitude with respect to Driven Frequencies

    Homework Statement A mass-spring system has b/m = \omega_0/5 , where b is the damping constant and \omega_0 the natural frequency. How does its amplitude when driven at frequencies 10% above \omega_0 compare with its amplitude at \omega _0 ? How does its amplitude when driven at...
  15. A

    Doppler Effect frequencies Question

    Homework Statement An object producing a sound with frequency 500 Hz is traveling at 40 m/s toward an observer, and the observer is traveling at 30 m/s away from the source. Another source producing a sound with the same frequency is traveling at 10 m/s toward a stationary observer...
  16. M

    Finding upper and lower bound superposition frequencies of ultrasound pulses

    Homework Statement Ultrasound pulses of with a frequency of 1.000 MHz are transmitted into water, where the speed of sound is 1500m/s . The spatial length of each pulse is 12 mm. a) How many complete cycles are in each pulse? b) What is the lower bound of the range of frequencies must be...
  17. J

    What are the frequencies of the fundamental and first two overtones?

    Homework Statement A guitar string is 90.0 cm long and has a mass of 3.17 g. From the bridge to the support post is 60.0 cm and the string is under a tension of 506 N. What are the frequencies of the fundamental and first two overtones? (f1,f2,f3) Homework Equations v=sqrt(FT/m/l)...
  18. O

    Help on Expected Frequencies Q2 & 3 - No Quotes

    I need help on question 2 and 3. For question 2, I think I got the expectation for Poisson distribution, but I have no idea how to get the normal one. Could someone provide me a formula or something? Thanks a lot!
  19. K

    AC analysis, multiple frequencies.

    Homework Statement http://www.aijaa.com/img/b/00322/3721717.jpg http://www.aijaa.com/img/b/00092/3721734.jpg Both supplies are basic sine waves and the frequency of the supply 2 is 100Hz. The assignment is to calculate the power that is transformed to heat (i.e the power the resistor is...
  20. J

    Fourier Transform Question - Negative Frequencies?

    When I see a graph of a Fourier Transform, or something in the frequency domain, say band-limited from -\Omega to \Omega, I'm confused to what the interpretation is of the negative frequencies. Physically it would seem as though something considered in cycles/second for example, should be...
  21. N

    Lowest Possible Frequencies of a Sound

    Homework Statement A loudspeaker at the origin emits sound waves on a day when the speed of sound is 340 m/s. A crest of the wave simultaneously passes listeners at the (x, y) coordinates (40m, 0) and (0, 30m). What are the lowest two possible frequencies of the sound? Homework Equations...
  22. cronxeh

    Amateur Radio: Lurking Frequencies & Conversations in NY

    So I did a little search and I can't seem to find any threads regarding amateur radio. Is anyone a ham out there and what frequencies do you lurk at and where? I'm a new ham, don't know why I decided to get into it but timing seems to be about right with new radios like Yaesu VX-8R and many...
  23. K

    How to find frequencies giving the coeffiecent friction and amplitude?

    A book is placed on a horizontal wooden plane that is undergoing simple harmonic motion with an amplitude of 1.0 m. The coefficiet of friction btween the book and the horizontal wooden plane is given by μ = 0.5. Determine the frequebcy of the horizontal wooden platform when the book is about...
  24. A

    Lower and upper cutoff frequencies

    Homework Statement i have values of input signal frequencies and relevant voltage gains(Av) of a amplifire.and i want to find upper and lower cutoff frequencies by drawing a graph.can someone tell me how to find upper and lower cutoff frequencies with following values. thanks here is...
  25. N

    Frequencies of the normal mode in standing waves in a string fixed

    hi,im a newbie over here,my physics quite poor so i really need help by understanding it,i jz wanted to ask could any1 please explain to me what is in phase,&out of phase?;im totally baffled.:blushingAnd what's frequencies of the normal mode in standing waves in a string fixed in both ends?i...
  26. D

    Which body absorbs frequencies of all kinds?

    i want to listen to radio on my mobile without earphone. so i need a very good wave absorbing material in d stereo jack. please suggest me some good metal that i can use as antenna.
  27. D

    Resonance/Harmonic frequencies in open/closed pipes

    Homework Statement The fundamental frequency of an open organ pipe corresponds to E above middle C (329.6 Hz on the chromatic musical scale). The third resonance of a different closed organ pipe has the same frequency. What are the lengths of the two pipes?Homework Equations natural frequency...
  28. C

    Smallest and largest electromagnetic frequencies

    What is the smallest electromagnetic frequency and the largest possible electromagnetic frequency? Also, can small frequencies ride on larger frequencies? Ergo. You are traveling 99.7 the speed of light away from something shooting a blue light light at you. What frequency is it? Once it...
  29. I

    Markov chain calibration to a set of cumulated frequencies.

    Homework Statement Hi! I have been given such a task: A population of firms can assume three states: good-bad-bankrupt (default) The cumulated frequencies of default (DP) from year 1 to 10 are given. Find an appropriate transition matrix (TM) I'm given a matrix of historical cumulated...
  30. B

    Maximum interference of frequencies

    A microphone is located on the line connecting two speakers that are 0.650m apart and oscillating in phase. The microphone is 2.25m from the midpoint of the two speakers. What are the lowest two frequencies that produce an interference maximum at the microphone's location? okay, so i have...
  31. S

    Energy of different frequencies of sound

    Take a two sound waves: for example let us spread them at both poles of the human hearing spectrum. The low frequency at 20Hz and the high at 20,000Hz. Which sound wave carries with it more energy? It is said that sound travels at 343m/s, is that true of all sound in the air medium...
  32. P

    Understanding of Bandwidth was that it is the Range of Frequencies

    Ok I seem to have a serious problem. My understanding of Bandwidth was that it is the Range of Frequencies that a Radio Receiver can let through its RLC Circuit (or known as the Bandpass Filter). I thought that The set of frequencies are such that they are larger than half the total power...
  33. W

    Natural frequencies - theoretical vs COSMOS results

    Hi all, I am new to the forum and am despreate for the solution for my current task. I am given a canteliver beam with the dimention: L =1250mm W= 75mm D= 30mm E=200 Gpa density = 7800kg/m^3 poison ratio=0.3 and I optained the first five natural frequencies from COSMOSWorks 2007...
  34. B

    Triagulating radio frequencies

    I was just thinking the other day about how they triangulate on radio frequencies. Imagine an illegal fm broadcast they are trying to find. From thought (not necessarily right), they would have 3 vehicles with receivers that would form a triangle and depending on angles and the time it takes...
  35. N

    Orbital Frequencies: Single Atomic & Covalent Electron Determination

    How are the orbital frequencies of single atomic electrons, and covalent electrons determined?
  36. A

    How Can Static Deflection Measurements Influence Gear Shaft Frequency Analysis?

    two small gears are attached to shaft that is supported by the self-aligning bearings A and B. the enginner designing the system would like to determine the natural frequencies of the system experimentally but dose not have the equipment necessary to do so. therefore, rather than ontaining...
  37. L

    Wavelengths of lowest and highest audible frequencies

    Homework Statement What are the wavelengths in air of the lowest and highest audible frequencies if te range of human hearing is 20 Hz to 20 kHz and the sped of sound is 342 m/s? Homework Equations v= \lambdaf The Attempt at a Solution v= \lambdaf 342 = 20 Hz \lambda \lambda = 17.1...
  38. I

    Waes: normal mode frequencies for 1 fixed extremity

    Homework Statement A String of length L has one of its extremities fixed and the other one loose. A. What's the equation for the normal mode frequencies? B. Draw a snapshot of the string for the 1st 3 normal modes Homework Equations wave equation The Attempt at a Solution...
  39. W

    Musical Instrument Project: Frequencies Aren't Right?

    (1) My requirement for this project was to build an instrument that can produce all the notes in a C scale. The accuracy of the notes is to be judged through Frequency (Hertz). I decided to build an instrument whose design is comprised of eight electrical conduit tubes (metal) that are about...
  40. N

    Solving a Wave Equation with Electric Fields of Different Frequencies

    Homework Statement I need to solve the following wave equation: [\nabla^2 + \frac{\omega_a^2}{c^2}\epsilon]\mathbf{E_a} = -\frac{4\pi\omega_a^2}{c^2}\mathbf{P}^{(3)} Homework Equations \mathbf{P}^{(3)}=\chi^{(3)}:\mathbf{E_1E_1E_2^*} E_1 and E_2 are two electric fields with...
  41. H

    Can Beat Frequencies Affect Light?

    I know how beat frequencies work with sound. I know they exist in RF so how do they affect light?
  42. E

    Light Frequencies: Exploring Visible & Beyond

    My first post... I'm studying physics at school (9th grade) and learned that light has lots of different frequencies above/below visible spectrum. I also know that the speed of light is a constant (300Kps). My question is, does light (all frequencies) travel together like one multilayered...
  43. O

    String Frequencies By Temperature.

    I'm working on some physics problems involving sound frequencies with string and wind instruments, and the current problem has the temperature drop from 20deg Celsius, to -12.7deg Celsius. Too my knowledge this problem disregards any wood expanding/contracting done by the instrument by the...
  44. I

    Canceling out low frequencies noises (subwoolfers)

    Here's an interesting problem that might be best solved by physics: Lets say your neighbors insist on using a loud subwoolfer late at night, it travels through your appartment walls and keeps you up all night. What would be a good way to cancel out the noise, other than earphones?
  45. U

    Any D/A converter and amplifier for microwave frequencies?

    At a time when pc's come with microprocessors clocked at frequencies of the order of 4 GHz, it must be possible to drive a D/A converter at microwave frequencies. Anyone know of hardware to do this? Anyone know of suitable hardware to transmit the waveform at a power density comparable...
  46. N

    Sinusoid to exponential w/ complex frequencies

    Homework Statement Express the given sinusoid in terms of exponentials and determine the complex frequency(s). 4(e^-2)cos(wt + pi/4) Homework Equations Euler's identity: A(e^i*theta) = A[cos(theta) + i*sin(theta)] The Attempt at a Solution I'm really drawing a blank here...
  47. arivero

    Is it possible to derive E=h f from E=h \nu in the theory of light quanta?

    If one reads the current version of the wikipedia entry on Photoelectric_effect we see that historically the postulate E=h f predates the relativistic theory. So it is kind of circular to argue in terms of E=h \nu to justify E=h f. The empirical process first postulated E=h f for the black...
  48. A

    Velocity of air, period, flutes and resonant frequencies

    Hi, We were talking about the speed of air expelled from the mouth as it passes over the embouchure hole of a flute, and I'm having trouble understanding part of the concept. At one point, in the notes, I have if the velocity of the airstream is greater than the period of the flute cavity's...
  49. M

    How To Fing Angular and Natural Frequencies WITH ANSYS ?

    How To Fing Angular and Natural Frequencies WITH ANSYS ?? Good Day every body, I am student in Ruhr Universität Bochum and I would like to ask please about the procedure how to find Natural and angular frequencies for a simple beam to get the idea fro it and to solve my proble. I will be...
  50. T

    Calculating Beat Frequency of 3 Frequencies

    Homework Statement If there are three frequencies: 200hz, 206hz and 209hz, how do you calculate the beat frequency of three frequencies? Homework Equations Fb=abs(F1-F2) The Attempt at a Solution
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