Amplitude Definition and 868 Threads

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. M

    Amplitude of field with phasor components

    Let's say I have a field (electric or magnetic or something) and it's time-varying so I choose to represent its components as phasors. Say the field is: \vec{F} = X\hat{x} + Y\hat{y} + Z\hat{z} where, X, Y and Z are complex numbers. Now, I want to find the amplitude of the field. If...
  2. S

    How Does Amplitude Influence the Oscillation Period of a Cantilever?

    1) Does the amplitude of a cantilever affect the time period of each oscillation when the experiment is set up like http://www.practicalphysics.org/go/Experiment_430.html 2) Please explain your answer. 3) The equation I am using is T= 2pi* sqrt ((4ML^3)/(Ebd^3)). Now this equation works...
  3. N

    Finding Amplitude for Horizontal Oscillation - 200 g Mass, 2.0 Hz

    Hello, I am having trouble finding the A in this problem. I found T=1/2=.5, I found K =31.55n/m. I tried using the formula KA2=MV2+KX2 to find amplitude but ended up with A=0.0435m This just doesn't seem right . I used .05m for a value of X. Does anybody know what I am doing wrong? A...
  4. A

    Period of Oscillation of Pendulum Varies with Amplitude

    Homework Statement Determine the period of oscillations of a simple pendulum ( a particle of mass m suspended by a string of length l in a gravitational field) as a function of the amplitude of oscillations. Homework Equations T(E) = \sqrt(2m) \int^{x_2(E)}_{x_1(E)}\frac{dx}{\sqrt(E-U(x)}...
  5. O

    Propagator/transition amplitude through intermediate integrations

    Hi all, suppose i want to calculate the propagator/transition amplitude which i can write as follows: (a,T|-a,-T)=\int_{-\infty}^\infty dx_1\int_{-\infty}^\infty dx_2(a,T|x_1,T_1)(x_1,T_1|x_2,T_2)(x_2,T_2|-a,-T). the situation is this: i already have an approximation of...
  6. Y

    Doubling Period and Amplitude: Object's Maximum Speed

    An ob ject moves with simple harmonic motion. If the amplitude and the period are both doubled, the ob ject’s maximum speed is I believe the object's maximum speed would be halved correct? Considering the regular velocity does not depend on the Amplitude and only the Period would affect it?
  7. I

    Solving Wave Equations with a Wall - Reflection and Amplitude

    Homework Statement We have waves propagating in the air. First part asks for a traveling wave solution in the x direction , given a wave length 2pi and amplitude 3m. I have obtained u(x,t) = 3 cos ( x - 345t). The question then asks what happens if a wall is placed at x=0, what is the form of...
  8. W

    Waves: find amplitude, given average power

    Homework Statement A sinusoidal transverse wave travels on a string. The string has length 7.60 m and mass 6.50 g. The wave speed is 34.0 m/s and the wavelength is 0.250 m. If the wave is to have an average power of 55.0 W, what must be the amplitude of the wave? Homework Equations...
  9. C

    Thin Films with consideration to Amplitude

    Homework Statement Consider the case of a film of thickness \lambda/4 with an index nf where nf<ng=1.5 that is applied to a glass surface. For minimum reflection the reflected rays r1 and r2 must cancel each other out. Since r1 and r2 both reflect fast to slow, they are in phase on...
  10. C

    Equation calculating the amplitude of a particle

    If I am right, it's supposed to be this: When a particle moves from r_{1} to r_{2}, the amplitude of the move can be written as: \langle r_{2} | r_{1} \rangle = \frac{e^{ipr_{12}/\hbar}}{r_{12}} where r_{1} and r_{2} are vectors of particle's position (I think?). and r_{12} = r_{2}-r_{1} and...
  11. B

    Relation between scattering amplitude and isospin

    Hi, I'm an undergrad physicist in a bit of a pickle over how isospin relates to scattering amplitude. It's been quoted to me that the scattering amplitude is given by the matrix element of the initial and final isospin states. I'd ideally like to show you this in latex, however I can't...
  12. L

    Amplitude and intensity of rock concert

    Homework Statement At a rock concert, the engineer decides that the music isn't loud enough. He turns up the amplifiers so that the amplitude of the sound, where you're sitting, increases by 87.0%. By what percentage does the intensity increase? Do not enter unit. Homework Equations...
  13. N

    Solve Amplitude & Period Homework: Spring Constant k=74 N/m, Mass 490 g

    Homework Statement A massless spring of spring constant k = 74 N/m is hanging from the ceiling. a 490 g mass is hooked onto the unstretched spring and allowed to drop. A) Find the amplitude B) Find the period of the resulting motion Homework Equations f = 1/T F=-kx x(t) = Acos...
  14. G

    Transmission amplitude using path-integrals

    Hello, As a path-integral newbie, I've been trying to calculate the amplitude for an electron which enters a box (potential within the box is given) at a point to emerge the other edge of the box (it doesn't matter when it exits). For simplicity, I first tried to work out the problem in one...
  15. S

    Mechanics help,find the particular solution and amplitude

    a block P of mass m lies on a smooth plane AB that is inclined at angle (alpha) to the horizontal.The block is attatched to the bottom of the plane,A, by a spring of stiffness 2k and natural length L0.The block is initially released from rest from the equilibrium position.the equilibrium...
  16. C

    Calculating Amplitude of a Wave at x = 6 cm | Dynamics Explained

    For the wave shown in this drawing, what is the amplitude at x = 6 cm? [Hint: Remember that the wave will be moving. So even though there presently is an node at x = 6 cm, this will change at a later time.] I put 0 cm as the answer but I got it wrong and I don't understand why it's not...
  17. R

    Summing cosines of different amplitude

    Hi there I am trying to sum many cosines of different amplitude and phase shift, but same ang. frequency (it's not a coursework question). My first thoughts are to sum them two at a time (to simplify matters?), probably using complex numbers. I tried doing it symbolically in MATLAB but it...
  18. T

    Amplitude of Standing Wave in Fundamental Mode

    Homework Statement A guitar string is vibrating in its fundamental mode, with nodes at each end. The length of the segment of the string that is free to vibrate is 0.381m. The maximum transverse acceleration of a point at the middle of the segment is 8200 m/s^2 and the max. transverse velocity...
  19. S

    Understanding Amplitude Modulation (AM)

    i hav got some doudts regarding AM (amplitude modulation) 1) the amplitude of carrier wave is changed according to the signal --- defn of modulation wats the amplitude of modulated wave is it A+B or other ... if "A" is the amplitude of carrier & "B" is the amplitude of signal ...
  20. T

    Maximum Amplitude, 50hx vs 60hz generator

    Homework Statement We have an AC generator with output current I. I, as a function of time, is a sine wave whose frequency, f, is the same as the rotational frequency of the generator. So, I(t) = I_{0}sin(2πft), where I_{0} is the max. amplitude of the current. In terms of magnetic...
  21. A

    Quadrature amplitude modulation

    Homework Statement The problem is about the http://en.wikipedia.org/wiki/Quadrature_amplitude_modulation" . This is a work from my course Analog signal processing. Here is the scheme http://img99.imageshack.us/img99/9449/zrgwj2.jpg Two things to do : 1. Find the expression of x_qam(t) 2...
  22. S

    How Do You Calculate the Amplitude for a Mass to Fall Off in SHM?

    1. There is a spring connected to a mass on a frictionless horizontal surface. Another mass smaller in size is placed ontop of the bigger mass. It asks find the amplitude so that the smaller mass falls off. Coeffient of friction is 0.4 between the two masses. K is given as 200 N/m 2...
  23. J

    How Do You Calculate Pressure Amplitude and Force on an Eardrum from dB Level?

    Some one please help! Pressure Amplitude Homework Statement (a) What is the pressure amplitude of a sound wave with an intensity level of 124.5 dB in air? _____ N/m2 (b) What force does this exert on an eardrum of area 0.520 10-4 m2? _____ mN 3. The Attempt at a Solution...
  24. J

    Answer Pressure & Force on Ear Drum: 33.576 N/m2 & 1.746 mN

    1. Homework Statement (a) What is the pressure amplitude of a sound wave with an intensity level of 124.5 dB in air? _____ N/m2 (b) What force does this exert on an eardrum of area 0.520 10-4 m2? _____ mN 3. The Attempt at a Solution if P is amplitude of pressure, then...
  25. J

    Pressure Amplitude of 124.5 dB Sound Wave in Air

    Homework Statement (a) What is the pressure amplitude of a sound wave with an intensity level of 124.5 dB in air? _____ N/m2 (b) What force does this exert on an eardrum of area 0.520 10-4 m2? _____ mN The Attempt at a Solution if P is amplitude of pressure, then sound...
  26. B

    Slope Amplitude: Physics Help for Newbs

    Ok as I am a Newb at pyshics I need some help with my homework. *sigh* This is going to be a couple of de de de questions. And here we go: 1. What does the slope indicate on a period(time) vs. amplitude(degrees) graph? 2. What does the slope indicate on a period(time) vs. length(cm) graph...
  27. A

    Archived Period, amplitude, maximum speed, and total energy

    Homework Statement A 175g mass attached to a horizontal spring oscillates at a frequency of 2.0Hz. At one instant, the mass is at x = 5.0cm and has Vx = -20cm/s. Determine the following. a.) the period b.) the amplitude c.)the maximum speed d.)the total energy Homework Equations...
  28. O

    Beating with signals of different amplitude

    Okay: here's the question: It's a well-known thing that when you add two sinusoids of equal amplitude and different frequency then you end up with a signal with the mean of the frequencies and a beat envelope. This just comes from the trig identity: \cos(a) + \cos(b) = 2\cos(\frac{a+b}{2})...
  29. H

    Two loudspeakers, finding amplitude.

    Homework Statement Two in-phase loudspeakers emit identical 1000 Hz sound waves along the x-axis. What distance should one speaker be placed behind the other for the sound to have an amplitude 1.60 times that of each speaker alone?Homework Equations None given, but I assume: v=f\lambda A =...
  30. Y

    How Does Amplitude Change After Multiple Oscillations?

    Homework Statement An oscillator with a mass of 500 g and a period of 0.300 s has an amplitude that decreases by 1.40% during each complete oscillation. If the initial amplitude is 11.4 cm, what will be the amplitude after 38.0 oscillations?
  31. W

    Solve Amplitude for Guitar String Vibrating in Fundamental Mode

    Homework Statement A guitar string is vibrating in its fundamental mode, with nodes at each end. The length of the segment of the string that is free to vibrate is 0.381 m. The maximum transverse acceleration of a point at the middle of the segment is 8600 m/s^2 and the maximum transverse...
  32. G

    What Is the Amplitude 3cm from an Antinode in SHM?

    Homework Statement Adjacent antinodes of a standing wave on a string are a distance 15.0cm apart. A particle at an antinode oscillates in simple harmonic motion with amplitude 0.850cm and period 0.0750s. The string lies along the +x - axis and is fixed at x=0. At time t=0, all points on the...
  33. F

    Probability Amplitude phases

    Quesion in approaching to Path Integral I've just read "Quantum Mechanics and Path Integral" book which was written by Feynman, he said the phase of probability amplitude is proportional to "the ACTION S in units of Quantum of action \hbar . What is the reason to be that? Can anybody explain...
  34. V

    Finding a frequency to create a given amplitude in a spring

    Homework Statement Damping is negligible for a 0.155 kg object hanging from a light 6.30 N/m spring. A sinusoidal force with an amplitutde of 1.70 N drives the system. At what frequency will the force make the object vibrate with an amplitude of 0.440 m? So: m=0.155kg k=6.30N/m F=1.70N...
  35. B

    How Many Oscillations and Amplitude of a Damped Pendulum in 4 Hours?

    Homework Statement Given: "In a science museum, a 110 kg brass pendulum bob swings at the end of a 15.0-m-long wire. The pendulum is started at exactly 8:00 a.m. every morning by pulling it 1.5 m to the side and releasing it. Because of its compact shape and smooth surface, the pendulum's...
  36. A

    Wave interference, finding amplitude in certain situations

    Homework Statement Two loudspeakers emit sound waves of the same frequency along the x-axis. The amplitude of each wave is a. The sound intensity is minimum when speaker 2 is 10 cm behind speaker 1. The intensity increases as speaker 2a is moved forward and first reaches maximum, with...
  37. K

    Amplitude of EM waves in vacuum ~

    Amplitude of EM waves in vacuum~~~ As we know, amplitude of waves decreases with distance due to energy loss. But what if EM waves in the space?? Since there's no matter around, I was wondering if there is any energy loss when EM waves travel through vacuum.
  38. M

    Calculating Time for Block to Reach Max. Amp. After Spring Collision

    Homework Statement A block of mass 0.28kg is attached to a spring of spring constant 12N/m on a frictionless track. The block moves in simple harmonic motion with amplitude 0.2m. While passing through the equilibrium point from left to right, the block is struck by a bullet, which stops...
  39. W

    E&M Method of Images: Amplitude Adjustment?

    The method of images exploits the fact any linear combination of solutions to a differential equation is also a solution, and the fields and potentials from a point source satisfy all relevant diff eq's, assuming the boundary conditions are met. However, a scalar multiple of any solution is...
  40. Alpha Russ Omega

    Particle speed relative to frequency and pressure amplitude.

    Homework Statement A sound wave of frequency 1250 Hz., propagating through air at 0 degrees Celsius, has a pressure amplitude of 15.0 Pa. What is the maximum particle speed (in meters/second)? Homework Equations v = frequency x lambda = (2 x pi x frequency)(lambda / 2 x pi) = omega / k =...
  41. M

    Amplitude Question Just Need A Formula

    At t = 0, a 730 g mass at rest on the end of a horizontal spring (k = 128 N/m) is struck by a hammer, which gives it an initial speed of 2.74 m/s. (a) Determine the period of the motion. s Determine the frequency of the motion. Hz (b) Determine the amplitude. m I have found parts A...
  42. marcus

    The LQG vertex amplitude (Rovelli, Engle, Pereira)

    this just out http://arxiv.org/abs/0705.2388 The loop-quantum-gravity vertex-amplitude Jonathan Engle, Roberto Pereira, Carlo Rovelli 6 pages "Spinfoam theories are hoped to provide the dynamics of non-perturbative loop quantum gravity. But a number of their features remain elusive. The best...
  43. E

    Amplitude of Sound Waves from Two Sources at a Point

    [SOLVED] Amplitude of Sound Waves from Two Sources at a Point Problem. Two sources, A and B, emit sound waves, in phase, each of wavelength \lambda and amplitude D_M. Consider a point P that is a distance r_A from A and r_B from B. Show that if r_A and r_B are nearly equal (r_A - r_B \ll r_A)...
  44. H

    Shallow water and small amplitude wave?

    Hi all. I am re-visiting again the origin of the KdV equation. On one hand, in the theory of small amplitude waves, the amplitude is assumed to be very small and hence the governing equations and the boundary conditions are hence linearised. On the other hand, having linearised the above...
  45. N

    Unraveling the Mystery of Wave Collisions: Same Amplitude Interaction

    Say we have two waves of the same amplitude are about to collide with each other. The preceeding wave travels at a slightly higher speed before interacting with the final wave. However, instead of passing through the final wave its speed and size is transferred into the final wave where it...
  46. M

    Best way to change amplitude of AC signal

    I am controlling a device with a 3-5kHz square wave. The device will attenuate an optical signal based on the voltage given to it, which should range from 0-5V (maximum of 20 V, but most extinction happens at 5V). I am wondering what the best way to go about doing this would be. I was...
  47. A

    Calculating Coefficient of Static Friction with Oscillating Masses

    Hi, Homework Statement There is a 2.0 kg mass riding on top of a 3.8 kg mass as it oscillates on a frictionless surface with a period of 3.0 s. The upper block just begins to slip when the amplitude is increased to 50 cm. What is the coefficient of static friction between the blocks? The...
  48. C

    Phase of an Amplitude Function

    In Feynman's Lectures on Physics, he constantly refers to the phase when discussing quantum mechanical amplitudes, but does not elaborate on what the phase means physically (e.g. the way the square of the amplitude gives the probability of finding a particle somewhere). So, if someone can...
  49. C

    Understanding Amplitude and Frequency Modulation

    hey everyone I really don't know whether this is the right stream for posting these kind of questions, but anyways here it goes.. Can anyone please explain to me the amplitude modulation and frequency modulation, or at least any website that xplains it, bcoz i am totally confused with...
  50. M

    Amplitude for paths in sample space?

    Is there any study anywhere considering paths through a sample space from one element to another? Is there an "amplitude" associated with these paths?
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