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. B

    Does Planck's relation apply to radio waves?

    I have some doubts about whether Planck's relation (E=hf) applies to radio waves. This has been bugging me because trying to apply Planck's relation to radio frequency results in some inconsistencies that I've been unable to resolve. BTW, I have no physics training, so please go easy on me...
  2. S

    Calculating the initial frequency of a decelerating flywheel

    I converted 5 minutes to 300 seconds, and movement angle per second as shown on the picture. From here on I am lost, as the angular velocity can't be calculated, as the time given isn't the one in which the flywheel does one rotation. I apologise if I used any expressions wrong, english is not...
  3. Negatratoron

    I Uncertainty between position and angular frequency - is this correct?

    Motivation: In my thermodynamics + statistical physics class, we derived the equipartition theorem for ideal gasses using Boltzmann factors, dividing the phase space of a gas particle in position+momentum space into units of size x*p=h based on the quantum nature of the space of states that are...
  4. hnnhcmmngs

    Calculating Collision Frequency of Electrons in Copper Cube

    Homework Statement: Verify the claim of Section 7.2 that the electrons of a metal collide with the surface at a rate of about 10^30 per second per square centimeter. Do this by estimating the collision frequency of electrons in a 1.00-cm cube of copper metal with one face of the cube surface...
  5. cnh1995

    Engineering Frequency of operation and Q factor of a coil

    My reasoning: Initial Q factor Q1= X1/R After doubling the frequency, reactance also doubles. So, Q2= 2(X1)/R. Hence, Q factor doubles (option a is out). Now, since it is mentioned that the coil has high Q factor, I assumed X >> R and hence, total impedance is approximately equal to the...
  6. KiwiJosh

    Wavelength to Frequency Relationship in Musical Notes

    Hi people, So I've been digging into music theory and want to understand the basic reasons for how it is constructed. I've come across a particular relationship but I can't understand the reason it exists. A quick musical lesson: Imagine you've got a pure musical note: let's say C. From a low...
  7. B

    Finding the frequency of very small oscillations

    So I'm working on this home assignment that has numerous segments. Firstly, I was asked to find the equilibrium distance between two particles in a potential well described by U(r). I did that by setting U'(r) = 0 and came out with r_equilibrium = 2^(1/6)*a. Now, I'm being asked to find the...
  8. Boltzman Oscillation

    Engineering Measuring the damping frequency from an oscilloscope reading

    I know the following equations for if the damping ratio is less than 1: $$\sigma = -\zeta \omega_n$$ $$\omega = \sqrt{(1 - \zeta ^2)\omega^2_n}$$ I am given the following circuit that I built on LTSpice: Measuring the voltage between node 2 and ground (blue), and the voltage Vc4(t) (green) I...
  9. S

    Comp Sci Calculating UART DLL and DLM contents from Baud Rate and Clock Frequency

    I understand that, Baud Rate = Clock Frequency / (16 x N) and that N = DLL + DLM when I substitute the figures to get an answer for N to be 576, how do I then convert this into the HEX contents of DLL and DLM, especially considering the maximum value for DLL or DLM is 255? I have uploaded...
  10. S

    Pendulum Clock -- Change in frequency with change in temperature

    1) I do not quite understand how the phrase remain accurate to 1 second in 24 hours? , means ΔP = 1 second, 2) I also don't understand how pendulum period P should be 24 hours What is the reasoning for both? The solution is as such P = 2π √(L/g) P' = 2π √((L+L α δT)/g) ΔP = P'- P = 2π...
  11. I

    I What happens to an electron's frequency during absorption of a photon?

    The point that I want to know is how two frequencys react with each other and does electron's frequency wait to reach to higher frequency on that fraction of second when they(photo's frequency and electron's frequency)collapse to each other than go to higher energy level or what?
  12. zzzriprip

    Uncertainty of an oscilloscope frequency, read from the period

    Hi, I am unsure of what uncertainty to get, so here is my full question: I used the CRO for an experiment, and since what I need is frequency, I read the period, so for the uncertainty of the period, it is the smallest division divided by two. So if my uncertainty for period is 0.001s, then what...
  13. piyush_1903

    Exploring Frequency & Temperature: Theory & Experiment

    So, my apparatus consists of a basic wooden plank with a nail on one end and a guitar tuner on the other. I plan on using a heating lamp to control the temperature of the apparatus, which is placed inside an insulation box, and use a non-contact infrared thermometer to measure the temperature of...
  14. nineteen

    How to find the frequency of the second wave?

    I don’t understand how to approach this. So I couldn’t make an attempt at a solution. Please help me understand better. Thank you in advance.
  15. Monoxdifly

    MHB Probability of Number 4 Appearing in 100 Tosses? - ASK

    A die is tossed 100 times. What's the expected frequency that the number appears will be 4? The probability is 1/6, so the expected frequency is 1/6 × 100, but that results in a fraction (16 2/3). Do we need to round it up or down? Is the answer 16 or 17?
  16. nineteen

    Does speed of light depend on the wavelength or frequency of it?

    I heard that the speed of light doesn't depend on the wavelength or frequency of it, how does it happen? I don't understand it because the ultimate equation is c = fλ (where c is the speed of velocity of light, f is the frequency and λ is the wavelength of it...).
  17. paulmdrdo

    Engineering Finding the center frequency and bandwidth of a Pass-band filter

    I tried solving this problem and got it correctly until the part A of the question. My solution is the same as the one given in the solutions manual until the part I put in the red box. I don't understand what is the logic behind the calculation of the bandwidth and center frequency there...
  18. Homgkung

    Can we find the frequency of a rod pendulum by just using F=ma?

    Summary: When I tried to find the angular frequency of a rod pendulum, I attempted to find its angular acceleration first, however, I realized that the results are different by using different approaches. i.e. (1) Newton's second law for a system of particles (2) Newton's second law for...
  19. M

    Fluid Interface Frequency Transform

    Hi PF! Fluid lies in a 2D rectangular channel and oscillates from a disturbance. I have several .csv files, each corresponding to a moment in time, where within each are two lists of numbers: the ##x## and ##y## position of a fluid interface. I'd like to decompose the interface into it's...
  20. E

    Equation for the frequency of light from an accelerating charge

    Say I have a electron in space, its accelerating along say the x-axis at 10 meters per sec^2, what frequency of light does it emit? Thanks!
  21. th078

    Radio frequency shielding for Raspberry Pi Zero

    So I'm trying to put together a Pi Zero mini computer to use for security-oriented applications, for example encrypting/decrypting messages, working with encryption keys, etc. It's cheap, very small and thus easy to carry around. However, I'm not entirely comfortable with the presence of the...
  22. novera

    Seemingly simple Physics 2 wave question (third harmonic frequency)

    I cannot find the correct answer anywhere online and the answer I keep getting is 5.4 (incorrect) Please show me the process to get to the answer! Thank you
  23. B

    How to theoretically derive the sideband frequency values?

    Hi If 2 signals of frequencies y1 = A cos ##\omega_1## t and y2 = A cos ##\omega_2## t are combined the resultant signal is given by y = y1 + y2 y = 2A cos (w1-w2)t/2 cos (w1+w2)t/2 If w1~w2 then one can plot the beat phenomenon from this equation. But if w1 >> w2 as in the...
  24. J

    Oscillator Frequency of a Ring Oscillator with RC feedback

    I'm not sure how will this oscillator work. Assume A is low, so B will be high and the capacitor will charge through B-C- 2Mohm. Now even D has gone high, so A will be high and B will be low and C will discharge. I'm not sure how the voltage divider rule across RC will take into effect. I found...
  25. J

    How to Solve a Doppler Effect Problem with a Moving Vehicle and Siren at Rest

    Pretending the siren is at rest in air: Wavelength = velocity/frequence --> (343 m/s) / 10,000 Hz = .0343m. I don't believe this is the correct way to go about solving the problem, since the vehicle is moving at the start and the siren is not at rest.
  26. A

    Permeability of copper in the microwave frequency range

    Relative DC permeability of copper is 1. Conductors are considered dispersive and therefore the permeability should change with frequency. Where can I find data or how can I calculate permeability of copper in Ghz frequency range?
  27. L

    Frequency response - Hydraulic network

    Hello everyone, i have a measured signal of a high pressure oscillation in a hydraulic network. Performing a FFT of said signal shows two dominant frequencies, a and b. After performing a linear analysis of the hydraulic network i found out that the network has two eigenvalues at those...
  28. W

    MHB Which class has the greatest frequency and which has the least frequency

    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​ frequency?
  29. J

    Is Dynamic CMOS an Effective Method for Frequency Division?

    I made a table using excel as: D is output. Like this I get Output frequency is same as input frequency. But I'm not sure if this is correct. PS: I'm aware I'm posting many questions, but I got interview exams coming up in August. Companies are going to come to university for recruitment and...
  30. P

    A Rabi frequency and "optical resonance and two level atoms" by Allen

    This might not really be that tuff a question, so the Rabi frequency... the definition that I seem to find in multiple locations seems to be in agreement with what's on wiki here: "https://en.wikipedia.org/wiki/Rabi_frequency" but when I am reading a book by L. Allen "optical resonance and two...
  31. N

    How to transmit a signal (530 - 550 Khz) to a point

    Hi everyone, I'm pretty new to electromagnetism and have no experiences in this topic. I have a signal generator (Digital Dual Channel Funktion Signal Generator) and want to generate two signals (530 and 550 Khz signal) and want to transmit these generated signals to the points on a table...
  32. J

    Doppler effect -- find the frequency

    I don't know what is wrong i think when bat gets sound f' = f×(c+v/c) when audience hears f''=f'×(c/c-v) f''=f×1.059 but it is wrong TT
  33. NP04

    Frequency of sound in an open-open tube

    I do not understand parts c and d. For part C I have no idea where to start. And for part d, I got 1/4λ = L (open-close tube fundamental harmonics) so λ = 4L. But the answer key says it is 1/2 L. Help!
  34. N

    B Planck Length: Upper Limit on Photon Frequency & Momentum

    Is it known how much momentum a photon possesses if it's wavelength is at the Planck length, and what happens if it's momentum is somehow increased from that?
  35. R

    Frequency to temporal period conversion

    I am working with signals that look like the following. The curve has the same form in both frequency and time domain. I am trying to calculate the ratio of two distances: The distance between two adjacent red "x"s (known as the free spectral range (FSR)). The distance between two adjacent...
  36. Engineer47

    Frequency Response of a Damped Car-Suspension System

    The quarter car system is represented by the above picture and I currently have all of the equations of motion and constants for each spring, mass, damper, distance, and moment of inertia. How can I find the frequency response with this information and knowing both tires hit a pothole of height...
  37. A

    Core material for high power high frequency coil/solenoid

    I read the limits of typical ferrite cores and it seems that most sources claim that they tend to work somewhere up to 1 Mhz. Surely they work great under that frequency, but is there any material that could provide a core material for a wide frequency range starting from few tens of Khz up to...
  38. koiuuuuuuuuuuu

    Calculating Shoe Size Frequencies: Understanding and Solving for Missing Data

    I 'am stuck at , what fraction of the shoes were size 4 I know the frequency is missing. The frequencies are 8,9,9,3,1. My thinking you how to add the frequencies and put 4 over it. Explain to me if I'm wrong. Thanks in advance
  39. S

    I Running through a complex math derivation of plasma frequency

    Background of problem comes from Drude model of a metal (not necessary to answer my problem but for the curious): Consider a uniform, time-dependent electric field acting on a metal. It can be shown that the conductivity is $$\sigma = \frac{\sigma_0}{1-i\omega t}$$ where $$\sigma_0 =...
  40. M

    How a square or sawtooth wave can have a certain frequency?

    Hello! I know that a square or saw tooth wave consists of infinite amount of sinousoids each having different frequency and amplitude. But when I look at their plot they seem to have a well defined frequency or period. Which term in the Fourier series determines their frequency? Does a saw...
  41. D

    Beat frequency and Doppler shift

    I found the beat frequency to be 4 Hz and the carrier frequency to be 260 Hz, but I'm not sure how to apply them to the solution/integrate the doppler and beat frequency equations?
  42. 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.
  43. 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​...
  44. 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...
  45. 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
  46. 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...
  47. M

    High frequency in MEMS devices

    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...
  48. 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...
  49. 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...
  50. 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?
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