What is Amplitude: Definition and 866 Discussions

The amplitude of a periodic variable is a measure of its change in a single period (such as time or spatial period). There are various definitions of amplitude (see below), which are all functions of the magnitude of the differences between the variable's extreme values. In older texts, the phase of a period function is sometimes called the amplitude.

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  1. H

    Damper Oscillator dropping amplitude to half the original value

    Homework Statement Consider a damped oscillator Assume that the mass is 318g, the spring constant is 104 N/m, and b = 0.106 kg/s. How long does it take for the amplitude to drop to half its initial value? M = 318 g Or 0.318 kg K = 104 N/m b = 0.106 kg/s Homework Equations n / a The...
  2. P

    Do Light Waves Have Amplitude?

    Waves in general have three properties: frequency (related to wavelength), amplitude, and speed. When referring to light as a wave, it's wavelength and speed are always referenced but never its amplitude, and I was wondering if light has a fixed amplitude for all wavelengths or if it changes...
  3. A

    Why does repeated reflection increase amplitude?

    diamonds shine brightly because light inside them is reflected repeatedly within its walls.why this repeated reflection increase the brightness of light??
  4. J

    Solving Wave Interference: A Study of Frequency & Amplitude

    Homework Statement Write a wave in one space dimension as ARe(ei(kx-wt-d))where A is the amplitude of the wave. Find a second wave of the same frequency such that the sum of the two vanishes at x = 0 and x = L. Assuming the wave velocity c = w/|k| is fixed, for what frequencies ! is this...
  5. Q

    Relationship between the vibration amplitude and the acoustic radiation

    Hi ! I need your help ! I have been kind of stuck with the following problem for a few days : I made measurements on a plate radiating sound with an accelerometer and I found very low values of displacement(1-10 pm !). It seems very very very low (less than 1 atom !) Depending on the...
  6. N

    Amplitude of vibration Effecting Frequency.

    1. Does the amplitude of a pendulum's vibration have effect on its' frequency? 2. F prop. to L or F prop to 1/Square root L where L is length and F is frequency. 3. Absolute Failure. Cannot Re-Do experiment due to lack of equipment.
  7. genxium

    How Fourier Expansion indicates the Amplitude w.r.t a certain frequency?

    Homework Statement I want to know how could I extract the amplitude(of the sinusoid component) of a random continuous wave w.r.t a certain frequency response? The teacher said the Fourier Expansion can do that but I'm really confused by the limits and integrals. Homework Equations...
  8. B

    Oscillation amplitude in oscillator

    Homework Statement The circuit in attached figure behaves as an oscillator. What is the oscillation amplitude? 2. The attempt at a solution With H(s), I've calculated the oscillation condition: KM \geq L_1+L_2, and the oscillation frequency: \omega = R_1/\sqrt(L_1 L_1 - M^2) How can I...
  9. P

    Conjugate of amplitude with imag. # in exponent and out of exponent?

    When you have i*e^(i@) as an amplitude, when you conjugate, do both i terms switch signs? I tried this and keep getting wrong answer. Thanks in advance. BTW this has to do with spin half particles.
  10. D

    AC Voltage and current, amplitude, rms, peak value

    General enquiries (template may not be suitable) - When the question provides value of AC voltage amplitude, is this the same value of peak voltage? - Also, in current waveform, when do we use peak current and rms current? - In ohm's law equations we use rms current, so in the current...
  11. P

    Stationary Waves - Effect of Frequency and Amplitude

    Hi, As part of my Physics Class, we created a spreadsheet that animates to waves moving in opposite directions to illustrate standing waves. In order to test we were told to put the same values of amplitude, wavelength and speed (frequency was calculated from wavelength and speed) for both...
  12. F

    Amplitude of small oscilliations

    Homework Statement http://img717.imageshack.us/img717/418/unlednsf.th.png The amplitude of small oscilliations for the bob is x0, and the amplitude of small oscilliations for the cart is y0. The length of the pivot is l . What is the maximum velocity of the bob relative to the Earth ...
  13. C

    Squeezed coherent states- amplitude and phase

    I'm brushing up on squeezed coherent state and have seen them defined in terms of position and momentum squeezing and in terms of amplitude and phase squeezing...is there a relation between the two? Am i missing something obvious :p ?
  14. G

    SHM: Frequency & Period Unaffected by Amplitude

    The frequency and the period of Simple harmonic motion don't depend on the amplitude. Meaning that changing the amplitude of a simple harmonic oscillator doesn't affect its frequency.. amplitude is the max displacement. Doesn't it make sense that if the max displacement is larger, then time...
  15. H

    AC Signal Amplitude Modulation in Resonant Tank Circuit

    I recently simulated a parallel resonant tank circuit on multisim. I put an oscope across the tank circuit and I get an AC signal, but what interests me is that it is amplitude modulated. The oscillations slowly build up in amplitude, hit a peak and then die back down. I think that the...
  16. R

    Calculating resultant amplitude, given 2 ampli's and phase diff

    Homework Statement Two waves of the same frequency have amplitudes 1.02 and 2.27. They interfere at a point where their phase difference is 59.5°. What is the resultant amplitude? Homework Equations Resultant Amp = (Amp1 + Amp2)cos(theta/2) The Attempt at a Solution Okay this...
  17. S

    For Amplitude Modulation, it is understood that the bandwidth of a

    For Amplitude Modulation, it is understood that the bandwidth of a passband signal is always twice as much as that of a baseband signal, for example if the bandwidth/max frequency of a message/baseband signal is 1 kHz and a carrier of 1 MHz is modulated with this baseband, then a "sum"...
  18. B

    SH driven oscillator amplitude at resonance equation

    I found via this forum the hint to use the inverse squared equation to differentiate to find the resonance frequency from the amplitude equation (equilibrium not transient solution). Thank you! (AlephZero?) When substituting the resulting frequency for the resonance into the amplitude...
  19. P

    Finding the amplitude of a pressure wave

    Homework Statement The sound level in decibels is typically expressed as β = 10 log(I/I0), but since sound is a pressure wave, the sound level can be expressed in terms of a pressure difference. Intensity depends on the amplitude squared, so the expression is β = 20 log(P/P0), where P0 is the...
  20. O

    Does the amplitude of a wave change with the Doppler effect in a medium?

    Does the amplitude of a wave changes when the source is moving? I am mainly interested in waves in a medium (e.g. sound, water...) No text about Doppler effect I have found mentions anything about the amplitude so I guess it does not change. However in the case if the speed of the source...
  21. H

    Negative sign in hopping amplitude

    Might be a naive question. In many places, specially in the Hubbard model, people use a minus sign before the tight-binding hopping amplitude. What does the negative sign signify for? Any special intention? Thanks.
  22. A

    2 Quant. questions (expanding an abitrary state, transition amplitude?)

    Homework Statement 1) The position operator x has a continuous spectrum of engenvalues {x'} with corresponding eigenkets {|x'>}. Expand this state in terms of the position eigenstates. 2) Suppose the transition amplitudes c_a',b' = <a'|b'> are known where {|b'>} are the eigenstates of a...
  23. L

    Reflection of a Wave on a Wall: Amplitude Calculation

    Homework Statement A wave with the amplitude 4 cm travels along a rope that is fixed to a wall. The wave reflects from the wall. What is the amplitude of the reflected wave? Homework Equations I know it's something with light, could you explian in more detail? The Attempt at a Solution
  24. N

    Amplitude of a simple harmonic motion equation

    if you have the equation: x(t) = Acos(ωt + ϕ) and you have the following information: A 200 g block hangs from a spring with spring constant 10 N/m. At t = 0s the block is 20 cm below the equilibrium position and moving upward with a speed of 100 cm/s. The answers give a short method of...
  25. C

    What is a probability amplitude?

    Hi What is a probability amplitude - I have read the article on wikipedia and I still don't get it. Hope someone out there can explain it to me.. Thanks
  26. N

    Calculate Amplitude using Decibels

    I have got an assignment in which i need to compare wave interference, so i am going to use decibels readings which i had gotten from experiments and the reference amplitude which is 60 to calculate this very very confusing task. i have gotten these formulas derived from which i derived...
  27. D

    Is there a spectrum difference in amplitude modulation with a sine or cosine?

    If I modulate a pulse X(t) with a.) a sine wave or b.) a cosine wave, I have the frequency spectrum expressions a.) \frac{1}{2j}[X(f-f_0)-X(f+f_0)] b.) \frac{1}{2}[X(f-f_0)+X(f+f_0)] When I plot these for a pulse, I see a difference in the magnitude spectrum, but I should not expect...
  28. S

    Why is any wave defined by the wavelength, but not by the amplitude?

    Any wave is identified by its wavelength (or frequency), and the wavelength is the distance between the two consecutive crests (or troughs) in wave trains. But wave is not identified by its amplitude. The wave could have been described by the amplitude as it doesn't require two wave trains (or...
  29. M

    Calculating Amplitude of a Simple Pendulum

    Homework Statement A simple pendulum consists of a spherical bob of mass 0.052 kg and diameter 1.1 cm attached to a thread of length 920 mm. b) The bob is released at rest with the thread taut at an angle of 5 degrees to the vertical. Calculate: i) the amplitude of the oscillation...
  30. Disconnected

    The amplitude of EM radiation

    Aight, so I have this problem where I think about something and then I understand it, but then instead of stopping thinking and understanding it, I keep thinking and stop understanding it. Unfortunately then my poor brain is so confruzed that I am unable to backtrack to understanding, and I...
  31. I

    Is amplitude always perpendicular to the rest axis?in a wavelength

    Is amplitude always perpendicular to the rest axis? in a wavelength amplitude it the distance between either the crest or through from the equbilium line. then in the case of transverse vibration, what is its amplitude? thanks
  32. E

    Why is the amplitude of wave guide indepentent of z?

    Griffiths p406 it talks about Guided waves http://img593.imageshack.us/i/imageyyf.jpg/ please see this photo... Hmm...Why are both of "E0、B0 independent of z? Is it about the fact that it propagate down the tube along z axis?
  33. U

    How to get amplitude and phase

    hello, if I have a sinusoidal signal that has changing amplitude and phase with respect to time, how can I find the amplitude and phase with respect to time? So given x(t) the probem is to find a(t) and p(t)? Thanks.
  34. J

    Amplitude of a Pendulum: Finding the Swing Range

    Homework Statement The horizontal end points of the swing pendulum are 10 cm apart. What is the amplitude of the pendulum. Homework Equations v=f(lamda) The Attempt at a Solution
  35. J

    Many worlds and probability amplitude. What does it represent?

    Is there any statement which perfectly captures what the probability amplitude, in the many worlds interpretation, represents? To say that there is an x chance of y happening is non-sensical because, according to the interpretation, y WILL happen in at least one universe. To say that there is...
  36. jegues

    Resultant Amplitude of 2 Waves

    Homework Statement Two sinusoidal waves have the same angular frequency, the same amplitude ym, and travel in the same direction in the same medium. If they differ in phase by 50 degrees, the amplitude of the resultant wave is? Homework Equations The Attempt at a Solution How do...
  37. PainterGuy

    Full wave rectification using CTT and amplitude of output waveform

    Hello, :smile: I did an experiment on full wave rectification using center tap transformer. The transformer read: Input 220V, Output 12V, 12V. I used two diodes and 1 micro farad capacitor. As you see capacitor's capacitance is very little so it didn't effect the overall output because I...
  38. S

    Making Amplitude of Oscillation the Same

    Homework Statement What value must be equal for two different masses to oscillate with the same amplitude? Homework Equations x(t)= Acos(wt+p) v(t)= -Awsin(wt+p) The Attempt at a Solution The answer is (xo)^2+(w*vo)^2 But I really don't understand why... does it have something...
  39. B

    Can the intensity of soundwaves be affected by the size of a gap?

    Ok so I was sitting out back one day listening to some music with some friends around. We had some music playing on a stereo inside the house and we were out the back with the glass door open about 10 cm's. I thought I noticed that some sounds with different frequencies seemed louder then...
  40. R

    Biophysics: Amplitude of the pressure wave.

    Homework Statement Say that the logarithmic intensity of a dolphin's sound is 50dB as measured as 1m away. What would be the ampltude of the pressure wave at 20m from the dolphin? My Question/Problem: How are you supposed to factor in the 20m away? Homework Equations Po=...
  41. M

    Find the amplitude and phase shift of an oscillating spring?

    Homework Statement A 205 g mass attached to a horizontal spring oscillates at a frequency of 4.60 Hz. At t =0s, the mass is at x= 6.00 cm and has v_x =- 34.0 cm/s. Determine Amplitude and Phase Shift. Homework Equations x(t)=Acos(\omega*t) \omega=(2*\pi)/T T=1/f The Attempt at a...
  42. H

    Understanding the Relationship between Amplitude & Loudness of Sound Waves

    Homework Statement two sound waves of the same frequency have respective amplitudes of 3 units and 1 unit and are traveling in opposite directions in the same straight line.At a particular place in that line ,the resultant wave will vary in loudness.The ratio maximum loudness/minimum loudness...
  43. S

    Does expansion of spacetime also stretch amplitude of light waves?

    Expansion of spacetime stretches wavelengths and produces the red shift. Does it also stretch the amplitude of the wave, and make distant stars look brighter and therefor nearer?
  44. S

    Amplitude of wave stretched as well as red shift?

    The expansion of spacetime stretches and red shifts the wavelength of light. Is the amplitude of the wave stretched as well? So that very distant stars appear brighter, and therefor nearer?
  45. K

    What exactly is the amplitude spectrum of the Fourier Transform?

    Homework Statement Not really a homework question, but related none the less. I'm confused about what exactly the amplitude spectrum is. As well as the power spectrum. Homework Equations Not really taking a purely mathematical approach here, I'm using numpy for python. Specifically the fft...
  46. N

    Amplitude of a wave when changing depth

    In most books the amplitude does not change when water waves pass from deep to shallow water. In some books the diagrams show an increased amplitude. Which one is correct?
  47. P

    Frequency of the carrier wave changed during amplitude modulation

    While reading about frequency modulation, I found that it was clearly written that the amplitude of the carrier wave remains unchanged. However, i didn't find a statement stating that the frequency of the carrier wave remains unchanged for amplitude modulation. So, is the frequency of the...
  48. B

    Oscillation amplitude of block

    1.A block of mass M=1 kg rests on a frictionless surface and is connected to a horizontal spring of force constant k=25 N/m. The other end of the spring is attached to a wall. A second block of mass m=500 g, rests on top of the first block. The coefficient of static friction between the blocks...
  49. M

    What is the correct code for plotting an amplitude spectrum in MATLAB?

    i am trying to plot the amplitude spectrum for a function which has the following properties: f(t) = 1, 0 < t < 10 f(t) = 0, 10 < t < 20 the period of the function is 20 i found the Fourier coefficients to be Fn = -(1/n*pi)(cos(n*pi) - 1) i tried to use the following code to plot the...
  50. E

    : precalc project amplitude help

    URGENT: precalc project amplitude help! Homework Statement I am doing a project for my precalc class which explores the applications of sine waves in real life. I chose to do bat and dolphin echolocation. so far the information i have found online has given me frequency in Hz, length of each...
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