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. T

    Rogowski Coils - find amplitude of Emf

    Homework Statement When a wire carries an AC current with a known frequency you can use a Rogowski coil to determine the amplitude Imax of the current without disconnecting the wire to shunt the current in a meter. The Rogowski coil, shown in the figure, simply clips around the wire. It...
  2. S

    Finding amplitude and phase angle from a graph?

    I have a question asking for the period, frequency, amplitude and phase angle from simply looking at a graph. I have the period and frequency, and 'think' i have the amplitude (high point - low point / 2), but I don't know how to get the phase angle. No equation is given so I can't simply...
  3. N

    Finding amplitude of oscillator

    Homework Statement a 200g mass attached to a horizontal spring oscillates at a frequency of 2.0 Hz. At t=0s, the mass is at x=5.0 cm and has v=-30 cm/s. Determine: a) period b)angular frequency c) AMPLITUDE Homework Equations x(t)=Acos(wt+psi) v(t)=-Awsin(wt+psi) w=2*pi*f T=1/f...
  4. M

    Understanding Amplitude Modulation for Radios

    I'm learning about radios at the moment but there's a few things I'm not clear about concerning modulation. I'll use audio amplitude modulation as an example. Let's say I have a device which I speak into and this device converts the variations of the sounds waves coming outta my mouth into an...
  5. K

    Can Fourier Transformation be Used for Amplitude of a Free Particle?

    I hope this is the correct place for my question. I posted it here, because it`s from Peskin & Schroeder: "Consider the amplitude for a free particle to propagate from \mathbf{x}_{0} to \mathbf{x} : U(t)=\left\langle \mathbf{x}\right|e^{-iHt}\left|\mathbf{x_{0}}\right\rangle In...
  6. P

    Why do you need low amplitude oscillation in SNOM?

    Am I right in saying that a tapered optical fibre 'collects' light from evanscent field. Why would this mean it needs to oscillate as it scans a sample surface? Cheers! philip
  7. E

    Probability Amplitude and Time Evolution Operator

    Hello, I am fairly new to quantum physics (I'm actually an engineer, not a physicist). I think I am getting a decent grasp on things, but I have a question. Suppose you have two time dependent states: \Psi_{1} and \Psi_{2}. Also, suppose that we have a constant potential, represented in our...
  8. A

    Is the Amplitude Coefficient of Reflection Always 0 at 90 Degrees?

    At what angle of incidence is amplitude coefficient of reflection parallel to the incidence plane 0? my solution is that by Fresnell's equation, r//=tan(i-i`)/tan(i+i`)=0, i=i`,i=90.so for whatever surface,angle of incidence should be 90. is it correct? different from the answer!
  9. V

    How to Determine Amplitude and Maximum Speed in Spring Motion?

    A 0.38 kg mass is attached to a spring and executes simple harmonic motion with a period of 0.08 s. The total energy of the system is 1.9 J. Find: a) the force constant of the spring. Answer in units of N/m. b) the amplitude of the motion. Answer in units of m. For a, I got 2341.655 N/m...
  10. P

    Harmonic to have an amplitude higher than the fundamental

    Is it possible for a harmonic (produced by a stringed instrument) to have an amplitude higher than the fundamental. If so how?
  11. L

    Wavelength or amplitude < a Planick length?

    Is it possible for an object's size to be great enough to make it's wavelength or amplitude < a Planick length? If so, does it's position become certain, and, applying the uncertainty principle, can you not know the velocity?
  12. E

    EM Wave Amplitude: Questions & Answers

    Hi I hope this is the right place to post. I have some questions regarding EM wave amplitudes. There are some other posts in the past regarding this and some people replied by saying that amplitude of a light wave is equal/close to wavelength of the wave. This is deduced from the fact that...
  13. K

    How do you find the displaced amplitude of sound?

    Homework Statement A loudspeaker of 30cm diameter vibrates at 2kHz. Given that the pressure generated is 55.1N/m2, determine the displaced amplitude. Assume air density is 1.59kg/m3 and that the speed of sound is 340m/s. I have been told that the dimensions given for the loadspeaker is...
  14. P

    What is the Amplitude of a Pendulum?

    How can one determine the amplitude, frequency and period of an amplitude? this is not homework, i was just curious, because i knew how to find the time using the 2 pi sqrt(l/g), but wanted to know about this, since i am learning about waves and harmonic motion! Help would be appreciated...
  15. N

    Amplitude of oscillations depends on the amount of damping?

    Which one of the following statements about an oscillating mechanical system at resonance, when it oscillates with a constant amplitude, is not correct? A The amplitude of oscillations depends on the amount of damping. B The frequency of the applied force is the same as the natural frequency...
  16. H

    What amplitude will the input signal have when connected

    Homework Statement An experiment to monitor the sound level in a room is to be conducted using a microphone. The microphone (output impedance = 1 kO) produces a maximum amplitude of 5 mV when connected to an oscilloscope (input impedance = 1 MO). If RI = 1 kO what amplitude will the...
  17. N

    Finding Amplitude in Harmonic Function: Solving for Time t

    Homework Statement Hi all. I have the following harmonic function: V(t)=A\cos(\omega t)\exp(-Ct), where C is a constant, and A is the amplitude. I need to find the time t, where the amplitude is A/2. This gives me: V(t)=A\cos(\omega t)\exp(-Ct) = \frac{A}{2}, but how...
  18. T

    Amplitude of Electromagnetic wave?

    How come the energy of an electromagnetic wave depends only on its frequency? Given by E = hf. How come the energy depends only on the frequency of the wave and not on the magnitude of the E component of the wave? Doesn't the energy depend on the amplitude? Or is there no such thing?
  19. Z

    Wave energy ~ wave height squ. or wave amplitude squ.?

    Hello, I've found different formulas regarding wave energy. 1) Wave energy is proportional to wave length \lambda times wave height squared 2) Wave energy is proportional to wave period T times wave amplitude squared From what I've read, wave period is equivalent to wave length. But...
  20. 0

    Finding Amplitude of Oscillation for a Spring-Mass System

    Homework Statement A 100 g ball is attached to a spring with spring constant 2.5 N/m oscillates horizontally on a frictionless table. Its velocity is 20 cm/s when x = -5.0 cm. What is the amplitude of the oscillation? Homework Equations x = Acos(ωt +φ ) V= -ωAcos(ωt +φ ) The...
  21. N

    What Is the Oscillation Amplitude at Various Points on a Vibrating String?

    Homework Statement A 2.0 m long string vibrates at its second harmonic frequency with a maximum amplitude of 2.0cm. One end of the string is at x = 0cm. Find the oscillation amplitude at x = 10,20,30,40, and 50cm. Homework Equations A(x) = 2asin(kx) k= 2pi/wavelength The Attempt at...
  22. N

    Electrodynamics: Amplitude of currents

    Homework Statement Hi all. Please take a look at the attached circuit. I've have found the amplitude of the current through the resistance to be: \left| {I_0 } \right| = \frac{{\varepsilon _0 }}{{\left| {R - \frac{R}{{\omega ^2 LC}} + \frac{i}{{\omega C}}} \right|}}, where ε_0 is the...
  23. M

    Finding the Amplitude of a spring (Simple Harmonic Motion)

    [SOLVED] Finding the Amplitude of a spring (Simple Harmonic Motion) First post here at PF, so forgive me if I make a faux pas. I'm trying to study for an upcoming Physics test and I'm having a bit of trouble with this. Homework Statement A massless spring with spring constant 19 N/m hangs...
  24. J

    Quantum Amplitude: Find N, Probability & State |psi'|

    Homework Statement The eigenstates of two commuting operators A and B are denoted |a,b> and satisfy the eigenvalue equations A|a,b>=a|a,b> and B|a,b>=b|a,b>. A system is set up in the state |psi> = N(|1,2> + |2,2> + |1,3>) What is the value of the normalization constant N? A...
  25. G

    Question reg. Amplitude Modulation

    Given m(t) = 25cos(2*pi*1000t) and sc(t) = 75cos(2*pi*150000t), hence the AM signal equation is 75[1+0.333cos(2*pi*1000t)]cos(2*pi*150000t). Expanding it will yield 75cos(2*pi*150000t) + 12.5cos(2*pi*149000t) + 12.5cos(2*pi*151000t) and proceeding with Fourier Transform, i got delta functions...
  26. K

    How to find frequencies giving the coeffiecent friction and amplitude?

    A book is placed on a horizontal wooden plane that is undergoing simple harmonic motion with an amplitude of 1.0 m. The coefficiet of friction btween the book and the horizontal wooden plane is given by μ = 0.5. Determine the frequebcy of the horizontal wooden platform when the book is about...
  27. K

    How Do You Calculate the Amplitude of Oscillation for a Spring-Mass System?

    Homework Statement A 200 g ball attached to a spring with spring constant 2.50 N/m oscillates horizontally on a frictionless table. Its velocity is 18.0 cm/s when x = -5.00 cm. A. What is the amplitude of oscillation? B. What is the speed of the ball when x = 3.00 cm? Homework Equations A...
  28. A

    Frequency Response of NI Elvis Board: Calculating Amplitude Error

    I've run an experiment on an active filter. I am using the NI Elvis prototyping board. The frequency response is taken with the NI Bode analyzer and I saved the output data in a text file. The Bode analyzer amplitude spec is give as 12 or 16 bits, how do I calculate the amplitude error using the...
  29. G

    Amplitude and coefficient of friction problem

    Homework Statement A large block with mass 30 kg executes horizontal simple harmonic motion as it slides across a frictionless surface with a frequency of .75 Hz. A smaller block with mass 10 kg rests on it, as shown in the figure, and the coefficient of static friction between the two is...
  30. I

    Amplitude of a wave hitting a boat

    Homework Statement You are finding it a challenge to climb from one boat up onto a higher boat in heavy waves. If the climb varies from 2.1 m to 4.5m , what is the amplitude of the wave? Assume the centers of the two boats are a half wavelength apart. Homework Equations just used...
  31. D

    How Does an Impulse Affect Amplitude and Frequency in Oscillatory Motion?

    * A 200g block attached to a horizontal spring is oscillating with an amplitude of 3 cm and a frequency of 2 Hz. Just as it passes through the equilibrium point a shalock so trp blow exerts a force impulse on the that the speed of the block is increased by .5m/s. What are the new a) frequency...
  32. D

    How Does Amplitude Influence a Pendulum's Period?

    when does amplitude start affecting the period of the pendulum? I know large amplitudes do.. and I've tried looking it up but none of the equations out there make sense.. :S
  33. B

    Finding the amplitude an oscillator: Driven harmonic oscillator problem

    Homework Statement A car is moving along a hill at constant speed on an undulating road with profile h(x) where h'(x) is small. The car is represented by a chassis which keeps contact with the road , connected to an upper mass m by a spring and a damper. At time t, the upper mas has...
  34. A

    Pressure Amplitude Calculation for Sound Waves

    Homework Statement What is the pressure amplitude in sound wave with intensity level of 65 dB? The Attempt at a Solution My textbook does not provide any instruction on how pressure amplitude is related to the intensity level. It does not even define what pressure amplitude is. While I...
  35. G

    Why need *complex* probability amplitude?

    Does anyone know a deeper reason why the quantum mechanical probability amplitude has to be complex? Is it to incorperate time dependence? Or maybe the operator/eigenvector formulation is special and since it includes the scalar product, having complex variables is more general and...
  36. Q

    How Does Quantized Energy Affect Oscillation Amplitude?

    Energy and Amplitude of Oscillation An atom in a crystal lattice can be regarded as having a mass of 2.0E-26 kg attched to a spring. The frequency of this oscillator is 1.0E13 Hz. What is the amplitude of oscillation if the energy of oscillation is one energy quantum? I know E=nhv, here n=1...
  37. T

    Water Waves' velocity, wavelengh and amplitude

    I'm trying to make a simple water simulation for a platform game (some of you will probably think "why should I care what you need it for?" but the fact it's a platform game tells you what point of view the game has). When a body touches the surface of the water, it creates two waves, one for...
  38. V

    Max Amplitude of Underdamped Oscillation

    Hey all, I am having trouble determing how to get the max amplitude of an underdamped oscillation. Can someone please tell me where do I start form.
  39. G

    Calculation of scattering amplitude ratio for two different angles

    Hi all, since scattering amplitude is given as: f(theta) = summation over l(from o to infinity)(2l+1)/k exp(i(phi))sin(phi) Pl(cos theta).But what happen if i want to calculate the ratio of f(theta=0)/f(theta = pi/2). Can anyone tell me the value of Pl(0). Thanks
  40. B

    How can I calculate the amplitude of a wave using frequency and energy?

    I don't know if it's possible or not but I want to calculate the amplitude of a certain frequency. I Have the value of the frequency, the energy needed to give this frequency and say I can calculate the wavelength from the given frequency... So Is it possible to calculate the amplitude...
  41. H

    Amplitude of sound wave in by 50%

    Any kind soul to help me with this questions...i am stuck qn. The amplitude of vibration of a certain sound wave is increase by 50%. What is the corresponding increase in the decibel level of the sound? My attempt.. beta= 10 log ( I/Io) lets just take I = 2.0 x 10^-7 let just take...
  42. M

    Amplitude modulation using using BC107 transistor

    Homework Statement In my electronics practical class, i assemble a ckt of amplitude modulation using BC107 transistor ,but the modulated wave always has the same phase up and above , there is no phase difference b/w the upper and lower part of the wave . My teacher also couldn't...
  43. T

    How Does Doubling Mechanical Energy Affect Amplitude?

    what happens to the amplitude if total mechanical energy doubles? i thought, if there was enough mechanical energy in the spring, the amplitude would be at its maximum... like it would have stretched as far as it could, so doubling the total mechanical energy, would only make the periods...
  44. S

    Finding the amplitude and phase of two sinusoidal motions

    Homework Statement Determine the amplitude and phase of the resultant motion when two sinusoidal motions having the same frequency and traveling in the same direction are combined, if their amplitudes are 3.0 cm and 4.0 cm and they differ in phase by pi/2 radians. Homework Equations...
  45. S

    What am I doing wrong with finding the complex amplitude?

    Homework Statement i got to find the complex amplitude i know that w = 50Hz displacement was 30mm at time 0 and -14mm at time 12ms Homework Equations (displacement) = Acos(phase constant)cos(wt) - Asin(phase constant)sin(wt) The Attempt at a Solution so I've tried plugging...
  46. L

    Critical damping provides the quickest approach to zero amplitude

    Critical damping provides the quickest approach to zero amplitude for a damped oscillator. With less damping (underdamping) it approaches zero displacement faster, but oscillates around it. With more damping (overdamping), the approach to zero is slower. I got this from hyperphysics but I...
  47. F

    What is the amplitude of -sin(x/5 - p)

    if f(x) = - sin(x/5 - p) are given, then the amplitude must be -1, correct??
  48. S

    Wavelength and amplitude. Are they related?

    Hello everyone, I just want to ask a question. If higher the amplitude the particles move a larger distance right. So is the wavelength related to amplitude. The sound travels in circles right. So I'm bit confused here how they travel in circles and be a longtitudinal wave at the same time. Any...
  49. R

    CasebyCase: Halfing the amplitude of light

    Is there a way to reduce the amplitude of a light wave to half its value in one case and do nothing in the other cases? Three Cases: Case A: Light amplitude input is 2 - reduce to 1 on output (cut in half) Case B: Light amplitude input is 1 - output is 1 (do nothing/pass through) Case C...
  50. S

    Finding the amplitude with frequency and wavelength.

    A wave with a frequency of 190 Hz and a wavelength of 26.2 cm is traveling along a cord. The maximum speed of particles on the cord is the same as the wave speed. speed = wavelength X frequency
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