# Frequency Definition and 156 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. ### Same frequency sounding different

I was always thinking that frequency decides the type of sound we hear ( ex: high pitched squeaky sound). But then I read somewhere that loudness i.e. intensity can also affect the sound we hear. Still the quality of sound should depend only on frequency since loudness would simply make it more...
2. ### I Water Waves Over Obstacles: Higher Frequencies Grow, Not Decay

In general, it seems that higher frequencies of a wave dissipate more than lower frequencies. For sound waves, it explains why you can hear lower pitches from farther away. For a vibrating string or plate, the higher frequencies also dissipate first, with the fundamental fading last. For water...
3. ### Engineering Resonance in AC circuits

Here's my attempt at a solution.
4. ### Can someone give me a better intuition of bandwidth?

Can someone give me a better intuition of bandwidth. The way I see it, is that the bandwidth is the range of frequencies which a signal/wave is allowed to have. This doesnt feel complete though. For example, how can I explain that TDMA, FDMA and CDMA are similar in this sense. As far as I know...
5. ### Measuring the natural frequency of a spring-mass system driving force

Hi, On a driving force graph ##y = displacement (m)## and ##x = time## where the external force start at t = 0 and the system is in equilibrium at x=0, it's easy to find the driving frequency. $$F = \frac{\omega}{2\pi}, \omega = \frac{2\pi}{T}$$ and we can get ##T## easily with the steady...
6. ### Beats and Resonance - How to Find the Length With only Frequency?

So, my thinking was that we use the formula V=f(lambda) and substitute the f so, V = 440(lambda) but then i dont have another number to cancel or rearrange by. And since closed air columns have the fractions of 1/4, 3/4, and 1 1/4 (5/4), we could divide by those?
7. ### Why does the amount of Refraction depend on wavelength?

I understand that electrons of a material have a natural frequency of vibration and the refractive index results from the phase difference between the incident light's field oscillations and the field oscillations of these electrons...
8. ### Looking for an intuitive explanation for a mass-on-spring simple oscillator's frequency

I just noticed something that is a little bit of a different perspective on a mass-on-spring (horizontal) simple (so undamped) oscillator's frequency and looking for some intuition on it. There are many ways to derive that for a mass on a horizontal frictionless surface on a spring with spring...
9. ### Influence of initial shift on undamped frictionless forced oscillations

I have general equation for undamped forced oscillations (no friction) which is: I just wonder about,what type of motion should occur when initial conditions are both 0 (i.e v0=0 and x0=0). My intuitive expectation is that as there is no 'natural' oscillations at beginning,vibration has to be...
10. ### 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...
11. ### 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...
12. ### 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. ### Doppler Effect Problem

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.
14. ### 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...
15. ### Doppler effect -- find the frequency

I dont 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
16. ### Statistics: Frequency

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
17. ### 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...
18. ### 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...
19. ### 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...
20. ### 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 ?
21. ### 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...
22. ### 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, isnt 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...
23. ### Resonance of an Air Column

Homework Statement [/B] When a stream of air is directed over the end of a 40 cm long piece of plastic pipe, open at both ends, a sound is produced. (a) Explain why this occurs (b) If the bottom end of the pipe is covered, what will happen to the pitch of the sound? Explain Homework Equations...
24. ### Calculators Smartphones apps for accessing Quadcopter Drones

Is it feasible to design and development Smartphones apps which will access,control & monitor quadcopter Drones operating at 2.4 GHz & 9.8 GHz wireless frequencies? Thanks & Regards, Prashant S Akerkar
25. ### Resonance between spring and pendulum: Different frequencies

Hi. I have a spring with spring constant 30 N/m and a mass of 0.5 kg. With the mass at the bottom, the spring has the length 58 cm at rest. If I now pull down the mass and release it, it starts with a vertical oscillation, then the spring also starts to swing sideways like a pendulum and the...
26. ### I What is the highest frequency of electromagnetic radiation?

Title says it all. Also, if the frequency of electromagnetic radiation is limited, why? My guess is the wavelength is limited to the Planck length, and when I plug those numbers into the calculator, I get 1.855 * 10^43 Hz. The maximum (Edit: observed) frequency of a gamma ray is 3 * 10^20 Hz...
27. ### Different frequencies but same temperature increase (antenna and biological tissue)

Hi; Let's imagine that I have an antenna and a biological tissue. The antenna emits the frequency of 1e7 Hz and I have a temperature increase x. When the antenna emits the frequency of 3e7 and 6e7 Hz the temperature increase is the same. How can I explain?
28. ### Frequency spectrum of a clarinet

Hi. Usually, the clarinet is presented as acting like a pipe system closed at one end, which only allows for harmonics that are odd multiples of the fundamental frequency. I used the app "SpectrumView" by OxfordWaveResearch to measure the following spectrum: Fair enough, the amplitudes of the...
29. ### Why the Frequency of Light Does Not Change Through a Medium

My question is about why the frequency of light or another EM wave does not change while passing through a medium. We know their Speed decrease and wavelenght change but think about this analogy for ex i am 4 meters high and drop 5 balls in 5 seconds and my friend waits at ground he will receive...
30. ### Calculating frequency of the second harmonic

Homework Statement The fundamental frequency of a violin string is 283 Hz. Calculate the frequency of the 2nd harmonic. Known: f = 283 Hz Homework Equations v = fλ f(n) = n*v/2L λ= L v(sound) = 343 m/s The Attempt at a Solution λ = 343/283 = 1.21 m f(2) = 2*343/2*1.21 = 283 Hz. I'm getting...
31. ### I What would be a useful application for 10 Thz nano-antennas?

Reading: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3597338/ However I dont understand what a useful application for this is? can someone explain?
32. ### A Why is ##\omega_c \tau >>1## for several revolutions?

Hey, I read about charge carriers in semiconductors in a magnetic field. They write that for several revolutions ##\omega_c \tau >>1## holds. But I think for one revolution it is ##\omega_c \tau = 2 \pi##. (##\tau## is the scattering time) Why they do not write ##\omega_c \tau >> 2 \pi##...
33. ### Derivation of resonant frequency for SHM systems

Homework Statement My question here isn't a specific question that has been given for homework, but a more general one. For an assignment I have to 'derive an expression for the resonant frequency, ω0' for two different systems, the first for 'a mass M connected to rigid walls via two springs'...
34. ### B Showing/proving a physical relationship

I derived a relationship between frequency and tension of a string, accounting for tension's effect in the linear density of the string. So in a nutshell, the equation is more complicated and is in the form of f^2=aT^2+bT (f is frequency, T is tension, ab are constants involving the control...
35. ### Instrument to measure the frequency of sound

I need an instrument to measure the frequency of the sound of a vibrating violin string for a high school research essay. I tried using a Labquest and a vernier microphone to measure but it was way too imprecise. I need the instrument to very accurate in measuring Hz as the nature of my essay...
36. ### Y-intercept of a lambda square VS tension of standing wave

Hi all! I am doing an experiment where we create a standing wave by attaching a string to a hanging mass at one end and to a string vibrator at the other (the string passes through a pulley). When plotting the graph, the slope is inevitably 1/(u*f^2) where u is the linear density and f the...
37. ### Optimal values for power in an induction heater?

I really want to build a simple but powerful induction heater for hobby blacksmithing. Metal shaping and the design of the cooling system within the coils are not a problem. I need help understanding the electronics Obviously I must first use a transformer as a safety against "backlash" to the...
38. ### 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?
39. ### 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...
40. ### 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...
41. ### 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...
42. ### 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^2...
43. ### Harmonics on the 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...
44. ### Cambridge NSAA Question -- Measuring the speed of sound with a speaker and 2 echos

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...
45. M

### Question regarding phase shift between two signals

Homework Statement Two sinusoidal voltages with amplitude 15Volts and frequency 2,771Hz are separated in time by 68% of a period. What is the phase shift in degrees between the two signals? Homework Equations y= Asin(omega)(x-h) The Attempt at a Solution I know my A is 15 and I'm pretty...
46. ### Beat frequency question

Homework Statement Homework Equations ##f_beat=f_1-f_2## The Attempt at a Solution Why are the two different answers? Is it because the first question is asking for how often it fluctuates, and the other is actually asking for the frequency of the sound? Why is the resultant tone the...
47. ### Relationship Graph Between Frequency and Tension

Homework Statement After plotting a graph with frequency (f) of a wire on the y-axis and tension (C-Clamps) on the x-axis, a root curve was obtained. If the trend of the line is maintained, does it pass through the origin? Should it? Note: graph attached Homework Equations f is proportional...
48. ### What is meant by natural frequency?

An object only undergoes an oscillation when I act on it. If I push a spring, it will have a certain frequency, and if I push a different way, it will have a different one. What is meant by natural frequency? What is meant by resonance?
49. N

### I Question about finding resonant box dimensions

Hello! I hope I'm in the right place for this questions. In short, I'm a musical instrument builder. I'm looking at placing a piece of wood above a closed resonator box. The box (also made out of wood) will have a hole in the top that is centered under the piece of wood. I know the material that...
50. T

### How do i get the frequency of undamped motion?

Homework Statement The single wheel of an aircraft can undergo a max of 7500N at a vertical velocity of 8 m/s on landing. The vertical spring moves in SHM and has a stiffness of 600N/mm. The systems vertical damper has a damping coefficient of 38 x 10^3 Ns.m-1 Homework Equations F=Kx...