What is Sine wave: Definition and 117 Discussions

A sine wave or sinusoid is a mathematical curve that describes a smooth periodic oscillation. A sine wave is a continuous wave. It is named after the function sine, of which it is the graph. It occurs often in both pure and applied mathematics, as well as physics, engineering, signal processing and many other fields. Its most basic form as a function of time (t) is:

where:

A, amplitude, the peak deviation of the function from zero.
f, ordinary frequency, the number of oscillations (cycles) that occur each second of time.
ω = 2πf, angular frequency, the rate of change of the function argument in units of radians per second




φ


{\displaystyle \varphi }
, phase, specifies (in radians) where in its cycle the oscillation is at t = 0. When



φ


{\displaystyle \varphi }
is non-zero, the entire waveform appears to be shifted in time by the amount φ/ω seconds. A negative value represents a delay, and a positive value represents an advance.
The sine wave is important in physics because it retains its wave shape when added to another sine wave of the same frequency and arbitrary phase and magnitude. It is the only periodic waveform that has this property. This property leads to its importance in Fourier analysis and makes it acoustically unique.

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  1. S

    How to construct a Modified sine wave

    Homework Statement Is it possible to generate a simple modified wave using simple circuit design? I know there is plenty of inverter available in the market, but I wish I can construct 1 by myself. How can I get started? Homework Equations The Attempt at a Solution
  2. J

    What is the amplitude of a sine wave?

    Hi, I want to calculate the amplitude of the following: V(t) = Acos(2wt)+Bcos(3wt)+Ccos(4wt)+Dcos(5wt) Not really sure what approach I can take to do this. I was thinking of using some combination of the double angle formula to simplify each part, but I don't think that will necessarily...
  3. S

    Why on a oscilloscope does a.c current have a sine wave, whereas a d.c

    Why on a oscilloscope does a.c current have a sine wave, whereas a d.c current is just a straight line. I've tried to look it up, but the explanations on the internet are a bit to complex for me to understand as i am only in my first year of alevel. If anyone could explain this to me, as simply...
  4. karush

    MHB What are the Intercepts of the Sine Wave $y=\sin{2(x-\frac{\pi}{4})}$?

    $y=\sin{2(x-\frac{\pi}{4})}$ how do you find the x intercepts of this thot if 0=sin(2x-(pi/2)) then 0=2x-(pi/2) since sin(0)=0 but doen't look it still don't know how to convert this to latex K
  5. S

    Square wave to sine wave conversion

    Hello guys i am very new to this forum. I am doing project in digital radio. can you tell me how to convert square wave into sine wave of frequency range 88 to 108 MHz. Thanks in advance.pls suggest me a circuit
  6. A

    How does alternating current produce a sine wave over time?

    I've only taken one introductory class to DC circuits where we learned Ohms law and series parallel combined circuits. Now I'm in an introductory class to AC circuits and last night's entire lecture (first day of the semester) was just over my head. We didn't go over any fundamental concepts...
  7. D

    How do I calculate the RMS and average voltage of a sine wave with a DC offset?

    I have to calculate the RMS and average voltage of a sine wave with a DC offset. I have a peak to peak voltage of 11V and an offset which is -6V. I have the average voltage as -6V and RMS voltage as 7.15V. I calculated the RMS as follows: AC Vrms = 5.5/sqrt(2) = 3.89V Vrms = sqrt(3.89^2 +...
  8. D

    Calculating Frequency and Form Factor for Half Rectified Sine Wave

    1. Calculate the waveform frequency and form factor of a half rectified sine wave Ipk = Peak current = 11A Tp = Pulse time of sine wave = 0.02s T = Period = 0.035s 2. I have used the equations: Irms = Ipk*sqrt(f*Tp/2) Iave = (2*f*Ipk*Tp)/pi f = 1/T 3. I have waveform...
  9. H

    Square wave and sine wave inverter

    Hello, Suppose we have a square wave inverter, and at the output we put a low pass filter with cut off frequency of 50 Hz, then the output is sinusoidal with frequency 50Hz. Now let's take a sine wave inverter and at the output we have a low pass filter with cut off frequency of 50Hz, then we...
  10. sbcdave

    How can I use slope calculations to solve for sin(x)?

    Hi. I have been trying to find a way to create a function that I can use to solve sin(x) in my head. I'm familiar with the taylor series but a few weeks ago thought that f(x)= -(x^2)+1 might superimpose well over a sin wave and would be an easy way to approximate. e.g. from x= +1 to 0 would...
  11. Z

    Sound Wave Physics: X-Axis vs. Trough

    Hi, easy one but can't really get my head around it. The physics teacher today showed sound as Sine wave on an oscilloscope. If I was actually listening to this sound wave, where would it be silent, on the x-axis or at the trough? Please explain.
  12. H

    What are the frequency bounds of waves from sine wave additive synthesis?

    Hello, If I can make any number of waves (n) all with the same phase but all within a frequency range of 100-200hz, what are the ranges of frequencies I can make when adding them? So would I be able to make a wave with frequency 400hz, or 25hz, using additive synthesis and these constraints...
  13. N

    High Voltage Unipolar Sine Wave

    Hello! I'm trying to generate a low power, high voltage sine wave that is unipolar (so, peak to peak ranges from 0V to 300V). Ideally, I would like the ability to vary the frequency from 10Hz to 60Hz. Is there an ideal method of doing this? With lower voltage I would generate my sine...
  14. P

    Finding the center by area of a range of a sine wave

    hey. I used to be quite talented at math, but I've let my talent deteriorate in the ~10 years since my last calculus class. I have a problem which I'm sure I would have devoured easily back in my school days, but am having trouble with now. I am considering two points on a normal (0 to...
  15. 1

    Sine Wave Compress/Expand per 180

    Hello, I hope you can help me. I want to "alter" a sine wave. I would say "modulate", except that I was unsatisfied with the FM formula. Here's what I want, visualize this: 1) copy-n-paste an image of a sine wave into MS-Paint 2) select part of the image from wave top1-to-bottom1 3)...
  16. O

    Is it safe to run laptop and router on modified sine wave inverter?

    Hi! I recently bought an inverter that connects to a 12 volt battery and gives out 220volts AC current. It is rated at 1200W and it produces modified sine wave. The main question I am trying to solve is: Is it safe to run my laptop and dsl router on this modified sine wave? I have done a...
  17. R

    Angular frequency of sine wave

    Homework Statement Please see the attached picture. I need help finding the angular frequency. The answer is 1571 but I don't know how they arrived at the solution. From the picture it looks like the period is 2pi but this would give an angular freq. of 1. Homework Equations...
  18. B

    Complex Number Sine Wave Problem

    Homework Statement Two alternating voltages are given by: V1= 12 sin 200pi t V2= 18 sin 200pi t + pi / 3 i) Plot each wave form on the same axis for one complete cycle ii) Add both together and plot the resultant waveform on the same axis iii) Using complex numbers, confirm ii)...
  19. D

    Current from a sine wave signal

    Homework Statement Given a sine wave signal (20V PP) connected to a 10 kilo-Ohm resistor. Calculate the current through the resistor in terms of average, rms, and peak currents. What wattage rating should the resistor have? Homework Equations Vrms=(1/Sqrt(2))(Vp) V=IR The Attempt...
  20. D

    How Can I Make a Pure Sine Wave Inverter with Limited Voltage and Current?

    Hi i am a 3rd year electrical student, i have a limited knowledge about inverters. i am trying to make a pure sinewave inverter, my intial spec was to create a 1) boost converter dc to dc 2) 3 stage pwm using a bubba oscillator etc 3) using a filter. my supervisor for the project said i could...
  21. D

    Confidence intervals of amplitude and phase for a noisy sine wave

    Homework Statement I have two series of data consisting of samples of a noisy sine wave and need to determine the amplitude and phase and the confidence intervals. I determined the amplitude and phase but don't know how to calculate the confidence intervals, help! The Attempt at a Solution By...
  22. T

    High speed sine wave to square wave converter

    Hi guys, I need to convert a sine wave to square wave, sine wave is running at about 1.5 GHz, so I had an idea of using comparator, but I am afraid that most of the conventional op-amps can't support my speed requirement. Any advice and reference circuits please.
  23. B

    Designing 1MHz Sine Wave Oscillator for AM

    Dear All I want to design a 1MHz sine wave oscillator to be used as carrier wave for Amplitude Modulation. Which will be the best approach in terms of frequency and amplitude stability and why? Can the technique be implement using high slew rate op amp and also can we use crystal...
  24. W

    Sine Wave Analysis: Calculating Time Interval for % Power

    Hi All I'm in the process of developing a phase control circuit. I need to know the specific time that corresponds to a required % of max power to chop the sine wave of a mains. I know that there is someway of calculating the time interval for a percentage power using integration or some form...
  25. Philosophaie

    Find a Sine Wave Generator to Plot Excel Data and Extrapolate

    Does anyone know a Sine Wave Generator program that will plot Excel Data and extrapolate a a sine wave with its harmonics? I know MatLab will connect but will not make a fluid sine wave. Freeware suggestions welcomed. Any suggestions?
  26. H

    Creating a DC/AC Inverter with Pure Sine Wave Output

    Hello, Am trying to make dc/ac inverter with pure sine wave output, while am searching i found an IC which is SG3524 which can generate a pwm signal. Is it a good choice for pure sine wave output, and what is the difference between the pwm signal generated by micro controller and the pwm...
  27. F

    Sine wave generator without constant voltage

    In physics lab we were using a signal generator with sine wave to find the frequency of a circuit quite precisely. Unfortunately, we had trouble and when checked with a circuit with purely resistive impedance, voltage changed with the frequency of the sine wave. The signal generator is...
  28. J

    Help with 1kHz Sine Wave Setup for Mechanical System

    Hello, I need some help with the setup of a circuit. I am a mechanical engineering student and I am working on a mechanical system that employs the use of a sine wave at 1kHz, and the signal would need to be amplified to about 400-450V. It will be employed on a 24V DC system. I just need some...
  29. L

    Cant oscillate sine wave from bubba oscillator

    Cant oscillate sine wave from "bubba" oscillator hey i can't oscillate sine wave from "bubba" oscillator using pSpice. see the following attachment. can u please help me?
  30. M

    Sine Wave Addition: Standing Waves?

    If two sine waves have the same frequency and amplitude but have different phase shift do they still produce a standing wave? Thanks for the help.
  31. K

    Sine wave with variable frequency

    I'm trying to do something very simple... I'd like to have a sine function, where the frequency is controlled by a separate frequency function Something like this: g(t) = sin(2*pi*f(t)*t) Assume that f(t) = 20*exp(-2*t)+4 I would expect a sine wave that starts at 24 Hz and then...
  32. X

    Frequency Spectrum of a Real Sine Wave

    Hi. I'm doing a lab where we hooked up an RF signal generator at 1.25MHz/10dBm to a spectrum analyzer using a 50 ohm wire. Can anyone explain to me or link me to a place where I can read about why a real sine wave's frequency spectrum is not a pulse? Also, why would with a sweep from 1 Mhz...
  33. morrobay

    Y displacements in sine wave at (x) and (x + 2 wavelengths)

    Homework Statement A sine wave in + x direction with max amplitude of 1 wavelength= 2.85 m wavenumber, k = 6.28/2.85 m = 2.2 rad/m w=8rad/m frequency=1.27 cyc/sec vel.= 3.63 m/sec at x = 20m t= 5.5 sec at x + 2 wavelengths x= 25.7m t=7.07 sec by definition the y displacement is the...
  34. Phrak

    High-Precision 60 Hz Sine Wave Generator for Circuit Elements

    As a circuit element I need a 60 Hz sinewave with low harmonic distortion (maybe 1-2% max.) and precision amplitude (1-2% max) of about 2.5 volts. It should be syncronous with an input reference frequency. The reference is about 30KHz and is some as-yet-undetermined multiple of 60 Hz.
  35. K

    Pure Sine Wave Inverter design

    I would like to design a Pure Sine wave inverter for DC to AC rectification. I want to drive motors with this applicaiton. (At most 120VAC .5HP) I don't want to specify too much, because the main point here is design basics. With the right information, I should be able to design accordingly. I...
  36. P

    Why is Light in a Sine Wave Form?

    Why are light waves/X-rays/gamma rays/etc. in the form of sine waves, rather than, say, a zig zag wave, or even a straight line? I recently watched this youtube video explaining how to visualize ten dimensions: http://www.youtube.com/watch?v=JkxieS-6WuA&feature=related And wondered if photons...
  37. O

    Build In-Phase Sine Wave Generator 1KHz-12KHz Voltage Controlled

    Help! I need to build an in-phase sine wave generator with quadrature output and its frequencies are between 1KHz-12 KHz and it need to be voltage controlled Thanks for any help anyone can provide.
  38. 0

    Signal that is a sine wave plus an offset

    I have a signal that is a sine wave plus an offset. I would like to measure the dc component and possibly also subtract it from the signal later. The signal is very slow (10th of Herz) and the offset changes on the order of minutes. I thought it should be possible to get a time average with an...
  39. J

    Sine wave resonance using square wave input

    Hello All, I have been doing a few basic experiments with coils lately and I am trying to figure out the simplest way to drive a coil at its natural resonant frequency so that I can get the Q as high as possible. My only problem is that I don't have a sine wave generator that I can use. I...
  40. I

    Is a Sine Wave Always Transverse?

    hi all, pretty sure this is the wrong place to post this but it is a quick one so... is a sine wave always transverse? thanks
  41. G

    Sine wave to square/triangle wave.

    How are Square and Triangle waveforms produced from Sinusoidal waveforms? Thanks Greg
  42. P

    Power of a sine wave (electronics engineering)

    This is obviously an electronics question. In communication systems, to calculate the power of a sine wave, the formula below is used Power (Sine Wave) = 1/2 * (peak amplitude)^2 This formula is apparently a standard electronics formula. I'm trying to understand where it comes from. How...
  43. I

    Yet another trig (sine wave) question

    During a storm, waves pass a fixed point every 2s. The difference between the crest and the trough of any wave is 5.2m a) Write the equation of the sine wave that models the height of a point on the water wave. b) Graph using 0m as the trough My Answer: 2Pi / k = 2 k = Pi 2.6sinPi(x) I...
  44. I

    Another Trig question (sine wave)

    During a strong wind, a tall building, such as the CN Tower, can sway back and forth as much as 100 cm, with a period of 10s. b) Write an equation for this function, in the form y = a sin kx My answer: 2Pi / k = 10 10k = 2Pi k = Pi/5 y = 100sin(Pi/5)x Now my question is...
  45. I

    How Accurate Are My Calculations for the Engine's Piston Movement?

    A piston in a large factory engine moves up and down in a cylinder. The height, h centimeters, of the piston at t seconds is given by the formula h = 120sinPi(t)+200. a) State the amplitude and period. b) What are the maximum and minimum heights of the piston? c) How many complete cycles...
  46. S

    Sine Wave using a DAC/Microcontroller.

    Hello everyone. I am working on a present for a girl (hehe) which will play a wav sound from an SD card into headphones. So, I have an SD card connected via SPI to a microcontroller which then connects via SPI to a DAC. Right now I connected my DAC and now I am having problems outputting a...
  47. E

    Synthesised Sine wave VS Modified Square Wave inverters

    I am to contrast the difference between modified square wave, and synthesized sine wave inverter outputs. Am I to understand, that a modified square wave output is like a square wave, but the transtion to current flow in the other direction is delayed some at the zero point. This is to give...
  48. K

    Adding/Subtracting DC Offset to Sine Wave: Circuit Needed

    Hello I have a question regarding DC offset addition. I have a sine wave of Peak amplitude 2V. Now i have a DC signal of 0.4v. How do i add this DC signal to my sine wave? Similarly I'm having another sine wave of 2Vpeak but phase shifted by 180 from the first one. Now again i have 0.4v DC...
  49. shintashi

    Sine wave & reflection question?

    I seem to recall it is possible to change a wave's frequency, pattern, and amplitude by adding another wave to it. Is it possible to add a second wave to a Sine wave to turn it into a cosine wave of the same amplitude and how would you do this? I'm thinking if I had an amplitude 1 for the...
  50. N

    What is the PDF of a Sine Wave Cycle?

    Does anybody know what the pdf of a sine wave cycle is? Or perhaps how to derive it? The problem can be done numerically, but surely there is an analytic expression for this function? There is a numerical solution available at...
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