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. W

    Correlation functions vs. Scattering Amplitude

    Hi there, I am learning the basics of QFT at the moment. Could someone explain to me, in the case for any number of scalar fields, the difference between correlation functions and scattering amplitudes please? Correlation functions <0|T(\phi_{1}...\phi{n})|0> Does one always write the...
  2. G

    Fermi's Golden Rule (Decay Amplitude)

    This question relates to Griffiths: Introduction to Elementary Particles, p. 196 The process in question is a neutral pion decay into two photons. It is stated that because the secondary particles are massless, the amplitude for this process is: M(p_2,p_3) where p_2 and p_3 are the momentum...
  3. K

    Amplitude based energy to frequency based energy converter

    i need to know if i can convert the high amplitude low frequency based energy to low amplitude high frequency energy based energy in both the case over all power should remain constant.And frequency should be in the range of VHF not in microwave range.
  4. R

    Finding Displacement Amplitude of a Pressure Wave

    Homework Statement A traveling sound wave causes a variation in air pressure according to the equation: ∆P = 20.0 sin(15.5x − 5.32 × 103t ) where x is in metres, t in seconds and pressure is in pascals. What is the amplitude of the displacement of the air particles caused by this...
  5. A

    Calculating Amplitude in Simple Harmonic Motion

    My question is with part c, more specifically the calculating of the amplitude part. http://img691.imageshack.us/img691/1750/shmquestion.jpg The answer to the question is: [PLAIN][PLAIN]http://img80.imageshack.us/img80/8921/shmanswer.jpg I do not understand how to arrive at this...
  6. O

    Potential Barrier in Infinite Well: Equal Amplitudes Both Sides?

    Homework Statement The well is set up exactly like this https://www.physicsforums.com/showthread.php?t=397977&highlight=potential+barrier+inside+an+infinite+square+well. It is basically a infinite potential well with a barrier in the center. Basically I've got solutions for regions 1, 2...
  7. J

    Finding the forcing frequency to maximize the amplitude

    Homework Statement Consider the following underdamped oscillator governed by: u''(t) + ¥u'(t) + w02u(t)=Fcos(wt) (a) Find the ge... (b) The hom... (c) What is the forcing frequency w for which the amplitude R in the previous part attains a maximum? Show that it is always less than...
  8. C

    Transfer function from amplitude response?

    Hi, in the paper I've attached, they give a method for generating a polynomial g for the amplitude response of a filter that gives arbitrary flatness and roll-off characteristics. \frac{1}{\sqrt{1+g}} And then they say the transfer function can be easily determined from this, but they...
  9. E

    Finding Oscillation Amplitude?

    Homework Statement I have a problem where I am given the following values: Angular Oscillation Frequency which I have assigned to omega Spring Constant, which is k The system's kinetic energy in Joules. Phi is assumed to be 0 I am asked to find the oscillation amplitude at a certain...
  10. M

    Velocity for Spring Constant with Amplitude

    Homework Statement A 79.8 g mass is attached to a horizontal spring with a spring constant of 2.66 N/m and released from rest with an amplitude of 39.5 cm. What is the velocity of the mass when it is halfway to the equilibrium position if the surface is frictionless? Answer in units of...
  11. H

    Dynamic Analysis - What will be the amplitude

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  12. A

    What is the amplitude of the subsequent oscillations?

    A 375 g air-track glider attached to a spring with spring constant 9.50 N/m is sitting at rest on a frictionless air track. A 425 g glider is pushed toward it from the far end of the track at a speed of 96.0 cm/s . It collides with and sticks to the 375 g glider.a)What is the amplitude of the...
  13. N

    Calculating maximum amplitude of atomic vibrations

    Is it possible to predict theoretically the maximum amplitude of vibration that atoms of a metallic species, like Copper, will exhibit at a given temperature?
  14. L

    Wavelength, frequency, and E field amplitude from magnetic field equation

    1. The magnetic field of an electromagnetic wave in a vacuum is B_z= ( 3.0 uT )*sin(( 1.00*107)x - omega*t) , where x is in m and t is in s. What is the wavelength and frequency of this magnetic wave? What is the amplitude of the E field? 2. wavelength = 2pi/k frequency = f = 1/T =...
  15. K

    Complex amplitude of E-field and phase changes

    Hi, I'm looking through my notes on em waves in dielectrics and the fresnel equations and I've been stuck on this for a while. It states that if the complex amplitude = E0eiΦ is positive there is no phase change. However when the value is negative, the phase change Φ is π.. Why is that...
  16. H

    Double-slit diffraction with UNEQUAL source amplitude

    In the following I am always talking about fraunhoffer diffraction suppose you have two slits in a doulbe slit diffraction experiment which are both exposed to the same plane wave (say the same laser) as the original source of radiation. Usually, we expect that both slits will act as EQUAL...
  17. I

    Impulse on a pendulum, to maintain amplitude

    Hi I am doing some past exam questions for revision and have got stuck on part d) of the attached question. It is asking, if an impulse is applied to a pendulum, what magnitude of impulse is needed to maintain the pendulums ampiltude. If it helps the ratio of amplitudes from 2 successive...
  18. D

    Simple harmonic motion and amplitude

    Homework Statement A 2.10-kg block is suspended from a spring with a spring constant of 280.0 N/m. A 0.070-kg bullet is fired into the block from directly below with a speed of 220.0 m/s and is embedded in the block. Find the amplitude of the subsequent motion. -What fraction of the...
  19. L

    Amplitude of the induced voltage across the coil

    If anyone can advise that would be great. 1. The plane of a 5 turn coil of 5mm² cross sectional area is rotating a 1200 r.p.m in a magnetic field of 10mT. Q. Calculate the amplitude of the induced voltage across the coil Data: 5 turns c = 1200 rpm A = 5cm² B = 10 mT 2. φ =...
  20. M

    Finding the Resultant Amplitude & Phase: A Practice Problem

    Hi, this isn't homework but a practice problem. A particle is simultaneously subjected to three simple harmonic motions, all of the same frequency and in the x direction. The amplitudes are 0.25, 0.20, 0.15, and the face difference between the first and second is 450 and between the second and...
  21. M

    What is the Complex Exponential Form of a Trigonometric Function?

    Hi this isn't homework, just a practice problem I already have the answer too for my waves class: z=sin(wt)+cos(wt) Express this in the from Z=Re[Aej(wt+\alpha)] I know how to express sine in the form of cosine, and cosine in the from of a complex exponential, but I don't know how to do...
  22. M

    Help Finding Amplitude of Voltage Across Capacitor At Resonant Frequency

    Hi, here is the question: For part b) I have to find the amplitude of Vc at the resonant frequency with I=1A, I have found Zeq and well here are my equations: \frac{jwL+R}{\ jwRC-w^2LC+1} and I have the equation for w at the resonance:w= \sqrt[2]{\frac{L-R^2C}{\L^2C}} I know at the...
  23. J

    The influence of crossing angle on amplitude in cable to cable coupling

    Homework Statement Hi all, I have this project i have to write but i am having trouble getting the necessary materials to aid my writing. The project topic is the influence of crossing angle on amplitude in cable to cable coupling. It is a magnetic coupling problem and i am supposed to design...
  24. M

    Frequency At Amplitude of Voltage Across Capacitor Decreases

    Hi, I know the relationship between Vc and the frequency is Vc=I0/(wc)...and if the output amplitude isn't adjusted doesn't this mean that any increase in frequency results in a decrease in voltage? I am asking this because I did a lab and I had to "raise the square wave frequency, but don't...
  25. L

    How Do I Calculate the Time Constant from Oscillation Decay?

    Homework Statement A gust of wind hits a flagpole and starts it oscillating. After 10 s, the amplitude of its motion has decreased to 25% of its initial value. What is the value of the time constant? Homework Equations xmax(t) = Ae-t/\tau The Attempt at a Solution I know...
  26. E

    How Does Sound Speed Affect Pressure Amplitude in Ultrasound?

    Homework Statement Consider an ultrasound beam incident normal to a boundary between two media with the same density, but where the speed of sound in the second medium is 50 percent larger than that in the first. Calculate the ratio between the pressure amplitudes of the incident and...
  27. U

    Calculating Amplitude and Energy in a Damped Oscillator: A Homework Question

    Homework Statement An oscillator with a mass of 520 g and a period of 0.500 s has an amplitude that decreases by 1.00% during each complete oscillation. PART A : If the initial amplitude is 10.2cm , what will be the amplitude after 43.0 oscillations? PART B: At what time will the energy be...
  28. S

    How to determine Vibration Amplitude

    Hello Every one, When I am looking at the design of a vibration screen, I found that the claims from different source have different equation. Please have a look on the attachment. You can see "Claim 2 " is a more general approach but need to know spring constant k. while "Claim 1"...
  29. W

    Decrease in amplitude with distance from source

    Homework Statement A stone is thrown into a quiet pool of water. With no fluid friction, the amplitude of the waves falls off with distance r from the impact point as: A. 1/r3 B. 1/r C. 1/r1/2 D. 1/r3/2 E. 1/r2 Homework Equations I can't think of any wave function accounting for...
  30. G

    Small amplitude oscillations of a ball with water

    Homework Statement The interior of a thin spherical shell of mass M and radius R is completely filled with water and hangs from a ceiling on a light thread. The distance from the sphere's center to the hanging point is L, and the mass of water is m. Determine the change in the frequency of...
  31. D

    An explanation for the apparent gradient of tidal amplitude with latitude?

    I teach marine biology and have been presenting the traditional model of the equilibrium tidal theory (2 humps on rotating earth) as still presented in most basic texts, but have not been able to find the theory or presumed explanation for the apparent generally increasing amplitude in tidal...
  32. L

    Amplitude of harmonic oscillator

    Homework Statement I have a simple harmonic oscillator system with the driving force a sinusoidal term. The question is to find the general solution and the amplitude of the steady state solution Homework Equations I found the steady state part of the solution. It is of the form...
  33. N

    Simple Harmonic Motion and amplitude help

    Homework Statement A 0.50 kg particle executes linear harmonic motion about the point x = 0.0. At t= 1.0, it has a displacement x = 0.50m and a speed of 5.0 m/s to the right. The frequency of the motion is 2Hz. Determine (a) the spring constant, (b) the amplitude of the motion, (c) the...
  34. C

    Amplitude and Perceived Loudness

    Hi. If amplitude is doubled, is perceived loudness necessary doubled? If I recall correctly, we hear things on a logarithmic scale.
  35. L

    Another amplitude and oscillation problem

    Homework Statement A small earthquake starts a lamppost vibrating back and forth. The amplitude of the vibration of the top of the lamppost is 6.5 cm at the moment the quake stops, and 8.0 seconds later it is 1.8 cm. A. What is the time constant for the damping of the oscillation? _____...
  36. L

    Oscillation, Frequency, Amplitude etc Hmwk Problem

    Homework Statement A 200g mass attached to a horrizontal spring oscillates at a frequency of 2.0 Hz. At one instant, the mass is at x=5.0cm and has vx = -30cm/s. A. Determine the period. T= ____seconds B. Determine the amplitude. A =____cm C. Determine the maximum speed. vmax =...
  37. L

    Standing Waves: Same Amplitude & Frequency, Opposite Directions?

    Homework Statement Am I right when i say, "Standing waves are produced by the superposition of two waves with the same amplitude and frequency, and opposite propagation directions". If I am then why would it not be, the same amplitude and direction of propagation, but different...
  38. zonde

    Probability is square of amplitude or it's product with complex conjugate?

    I have seen discussion about it here but it is still not clear to me whether probability is square of probability amplitude or is it product of amplitude with it's complex conjugate. I looked in HyperPhysics http://hyperphysics.phy-astr.gsu.edu/Hbase/quantum/qm.html#c5" and it says it's product...
  39. S

    What is the resultant amplitude at X?

    Homework Statement Two wave generators S1 and S2 produce water waves of wavelength 0.5 m. A detector X is placed on the water surface 3 m from S1 and 2 m from S2 as shown in the diagram. Each generator produced a wave of amplitude A at X when operated alone. The generator are operating...
  40. Z

    Find Amplitude of Motion: v=-6.54sin(20.1t) (mks units)

    Homework Statement what is the amplitude of the motion v=-6.54sin(20.1t) (mks units) angular frequency=20.1 Homework Equations v=wAcoswt The Attempt at a Solution I think the wavelength is 6.54 since 20.1 is the frequency. v =6.2 m/s. I am missing time.
  41. K

    Calculating Amplitude for Different String Gauges in Guitar Tuning

    Homework Statement guitar scale= 25.5inch pitch A=440Hz string gauges 0.056inch, 0.053inch Hello folks, can anyone help me with formula that relates string tension, scale length, pitch and string gauge.. I need to be able to calculate the amplitude of different string gauges. Thank...
  42. K

    The amplitude equation of Brusselator

    Brusselor reaction can be represented as kinetic equations: dX/dt = A-(B+1)X + X^2Y dY/dt = BX - X^2Y in order to investigate the behavior of the system beyond tje instability(B is used as bifurcation parameter, the critical value is B_H= 1+A^2), I use multiple-scale analysis...
  43. T

    Maximum Oscillation Amplitude?

    An ultrasonic transducer, of the type used in medical ultrasound imaging, is a very thin disk (m = 0.12 g) driven back and forth in SHM at 0.9 MHz by an electromagnetic coil. (a) The maximum restoring force that can be applied to the disk without breaking it is 36,000 Newtons. What is the...
  44. T

    Transmission line relative amplitude question

    Homework Statement An annular sheet (i.e. a flattened ring) , of thickness t = 1mm and made of a material of resistivity 0.5 Ohm m connects the inner and outer conductors of an air spaced coaxial transmission line at a point on the line. A low frequency signal is fed into one end of the line...
  45. J

    Finding amplitude? SHM problem

    Finding amplitude? SHM problem Homework Statement A 245 g mass attached to a horizontal spring oscillates at a frequency of 3.70 Hz. At t =0s, the mass is at x= 4.40 cm and has v_x = -25.0 cm/s. Determine: Homework Equations I got the first two The Period= .27027 s The Angular Frequency=...
  46. E

    Relationship between light amplitude and intensity

    what is the relationship between amplitude and intensity...is intensity just the amplitude squared?
  47. W

    Amplitude paths and Markov processes

    In continuous Markov processes there is an idea of sample path. Starting at a point we follow the values of the process through time and find that almost surely the paths are continuous. In Brownian motion (Wiener process) the paths are crinkly curves, continuous paths of infinite variation...
  48. C

    Three light waves combine at a point find resultant amplitude and phase angle

    Homework Statement Three light waves combine at a point where their electric field components are E1 = Eo sin \omegat E2 = Eo sin (\omegat - 2\pi/3) E3 = Eo sin (\omegat + \pi/3) Find the resultant amplitude of the electric field ER at that point and it's phase angle\beta Write...
  49. D

    Calculating Amplitude for a Spring Oscillation with Hooke's Law

    I attach a 2 kg block to a spring that obeys Hooke's Law and supply 16 J of energy to stretch the spring. I release the block; it oscillates with period .3 s. The amplitude is: * 38 cm * 19 cm * 9.5 cm * 4.3 cm Can anybody help me with this? I can't figure out what to do or where to...
  50. J

    Amplitude Squared Proportional to Intensity?

    A^{2} \propto I When is it appropriate to use this formula? I don't understand how to use a proportionality. Say I have an amplitude A and I make it 2A can I use the equation to determine the intensity will increase by a factor of 4? I guess I don't know why it is a proportionality...
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