# 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. ### Intensity of central maximum when width of single slit is doubled

My answer is (D) but the correct answer is (B). I thought the intensity will be 4 times since the slit width is doubled and amplitude becomes twice. What is my mistake? Thanks
2. ### Can the Voltage Across a Capacitor Be Greater Than the Source Voltage in a Series RLC Circuit?

(a) Substituting the values, I get ##X_L=100\ \Omega##, ##X_C=666.67\ \Omega##. From this, I get ##Z=601\ \Omega##, ##I=49.9\ mA## ##V_R=9.98\ V##, ##V_L=4.99\ V##, ##V_C=33.3\ V## (b) It's possible for the voltage amplitude across the capacitor to be greater than the voltage amplitude across...
3. ### What is the max amplitude before the sand particles slip off the vibrating plate?

A horizontal metal plate connected to a vibration generator is oscillating vertically with simple harmonic motion of period 0.080 s and amplitude 1.2 mm. There are dry grains of sand on the plate. The frequency of the vibrating plate is kept constant and its amplitude is slowly increased from...
4. ### I Why do we say that wave amplitude tells us where we are likely to find the particle?

Why do we say that wave amplitude tells us where we are likely to find the particle versus where we are likely to find the wave from the particle? Isn't the later a more accurate description of the QM math?
5. ### Seeking advice on "simple" pendulum problem

[Mentors' note: moved here from the technical forums after the thread was already fully developed, so no HW template] Hello all! I have a problem which I am beginning to suspect I am either unequipped to solve, or which does not have enough details! I can see, in my mind, the problem, but I...
6. ### Constructive Interference from Speakers on an x-axis

The first part of this question asks for the maximum amplitude produced, which I found to be 12.86 Pa. I was able to set up the expression for the combined wave equations. However, I am struggling to understand how to set up and solve an expression to find the distance I could move one of the...
7. ### I Calc Ampl & Cross Sec: Electron + Positron to Photon + Z Boson

Looking to calculate the amplitude and cross section of the process: electron + positron to photon + Z boson. Basically the annihilation resulting in Z + gamma rather than gamma +gamma. My question is mainly about how to deal with the polarization states with the Z boson, since there are 3 and...
8. ### Electric field amplitude question regarding intensity calculations

My question is specifically with calculating the intensity. The book solution is I=P/(4*pi*r^2) but would this not give me a weaker electrical amplitude in the final calculation after plugging it in to I=(1/2)*√(ε0/μ0)*(E02) ?
9. ### I Amplitude of the maximums in single slit diffraction

Hello! I was trying to calculate the amplitude of the secondary maximums in the single slit diffraction. When I use the formula: $$I = I_0 (\frac {sin(\Delta \phi /2)} {\Delta \phi /2})^2$$ If I take ## x = \Delta \phi /2 ## and derivate I get that the maximum occurs when: $$x = tan(x)$$...
10. ### Intensity of a wave at half amplitude and twice frequency compared to a reference wave

TL;DR Summary: How do i find the intensity of this wave? I know I is proportional to amplitude / frequency squared, but I don't know what equation this comes from. And I don't know how to answer this.
11. ### Calculating Wave Amplitude & Wavelength in Water Pools

How would we model/calculate the circular waves in a pool of water (wavelength and amplitude) from a mass falling into it from a given height, and from a fountain of water falling into it continuously? Is there is a way to describe the initial configuration of the wave based on the stimulus...
12. ### Amplitude of a circular ripple at distance r from source

For this problem, The solution is, Does anybody please know another way to solve this problem? EDIT: Why do they assume that no energy is absorbed by the water? Many thanks!
13. ### A physics PhD students addicted to Computational Languages

I am a 4th-yesr PhD student in Theoretical Particle Physics. My work frequently involves computational stuff so I feel like addicted to developing and using computational techniques for solving physics problems. I am aimed at some topics involving computers for my postdoc. My current project...
14. ### A Calculate the exact or approximate length of one period of the wave function

The known expression of the wave function is where A is the amplitude, k the wave number and ω the angular velocity. The mathematical definition of arc length for a generical function in an interval [a,b] is where, in our sinusoidal case: For our purpose (calculation of the length in one...
15. ### Max amplitude of a diving board that will not toss a pebble off?

How am I supposed to solve this problem? I did it in a way that's analytically not correct at all lol.. As a first I was thinking about how to relate it to the motion equations to no avail.. (of course with having the condition that normal force board on pebble = force of gravity on pebble)...
16. ### Automotive Amplitude based frequency response simulation in Abaqus

Hi, I have inputs like displacement of a driving mechanism and then the frequency of concern . Displacement: 0.2 mm Concerned Frequency: 100 Hz I would like to evaluate a part with the input displacement applied to a node and not as base excitation. It can be sweep over the frequency range...
17. ### A Off-Forward quark-quark amplitude in momentum space

I am having difficulty writing out ##\bra{p',\lambda}\psi^{\dagger}(-\frac{z^-}{2})\gamma^0\gamma^+\psi\frac{z^-}{2})\ket{p,\lambda}## in momentum space. Here, I am working in light-cone coordinates, where I am defining ##z^-=z^0-z^3##, ##r'=r=(0,z^{-},z^1,z^2)##. My attempt at this would be...
18. ### Comp Sci Amplitude of Analog Filter Question

Question Answer;
19. ### A.C. power supply voltage amplitude questions

I know that the answer for A is 31.82. But when i look up B why is it zero? can someone explain please thank you
20. ### MHB -7.8.98 amplitude period PS VS graph. of cos eq

Find amplitude, period, PS, VS. then graph. ok I think these are the plug ins we use $Y_{cos}=A\cos\left[\omega\left(x-\dfrac{x \phi}{\omega} \right)\right]+B \implies A\cos\left(\omega x-\phi\right)+B \implies T=\dfrac{2\pi}{\omega} \implies PS=\dfrac{\phi}{\omega}$ ok I wanted to do...
21. ### Finding Spring Constant When Given Amplitude, Time, and Mass

I averaged the masses and times (which i took the time given and divided by 10 because in the problem it says you measure the time it takes to complete 10 oscillations) then plugged them directly into the T=(2(pi)((m/k)^1/2) and got the wrong answer. This is really confusing me because I don't...
22. ### SHM Find amplitude from ω and x

Hi, I have no idea what formula to use while given these values, basically, it fits no formula. Any thing could help? Many thanks in advance Correct answer is 65
23. ### Calculating Amplitude in Standard Model

Hi! I'd like to ask you if my calculation of the amplitude on the mentioned process in the Standard Model is correct. The three diagrams contributing at lowest order should be where in the middle one the two Higgs boson are NOT forming a quartic interaction vertex. My attempt at calculating the...
24. ### Peak of the amplitude resonance curve

Hi everyone, I'm stuck on how to show the peak of the amplitude resonance curve is at wd = w0√(1-1/2Q^2), where Q = w0/γ. My first instinct is to take a derivative of something and set = 0, but what eqn?Help?
25. ### Intensity and electric field amplitude

Hello. I am having some trouble to understand the resolution of this question. We could easily try to calculate the electric field relative resultant at the screen. The problem i am having is about the amplitude of the electric field: Generally, we have that the intensity part dependent of the...

35. ### A BCS energy and Cooper pair probability amplitude

This question is for those familiar with the BCS theory of superconductivity or familiar with R.D. Mattuck's book “A Guide to Feynman Diagrams in the Many-Body Problem.” I am working my way through the book, and I am stumped by some of the problems at the end of chapter 15 (superconductivity)...
36. ### A Electric charge amplitude mode superconductivity

Hello, I have a question about the Higgs mode in superconductivity. In this doc, it is said, page 12, that the Higgs mode has no electric charge. But it couples nonlinearly with the photon (in the Ginzburg-Landau theory there is a term A²h with A the vector potential and h the Higgs mode). So...
37. ### A Calculation of an amplitude using the Grassmannian approach (amplituhedron)

In the following review paper on scattering amplitudes, by Elvang and Huang: https://arxiv.org/abs/1308.1697 they calculate the amplitude for 6 particles with half of positive helicity and half of negative helicity in section 9.3.2. Their matrix C (a point in the relevant Grassmannian) is...
38. ### Amplitude of Feynman diagram in ##\phi^4## interactions

This is not really homework assigned to me but I wasn't sure where to post this. I'm trying to work through the book "Quantum Field Theory for Gifted Amateurs" by Tom Lancaster. I'm doing the questions on Chapter 19 to understand how to draw Feynman diagrams and work out their amplitude. One of...
39. ### Dampening force - find decrease in amplitude

So first I tried to find b. 0.454=(0.6)e^((-b/(2*11.6)*50) Anyways with some natural log algebra etc. I get b = 0.129378 But when I plug this into the same equation only changing mass to 17.7 kg I get 0.4998 or 50% when the answer should be 59.6%?
40. ### Electromagnetic wave equation - phase and amplitude

how we get "e^(ikr)"...? Plz ans me... Thanks
41. ### I Is there any physical significance to Wave Amplitude?

I am studying Quantum physics and I'm having some problems to understand what is the Wave Amplitude since I can't find a physical significance to it. Does anyone ever heard something that come close to a physical significance?
42. ### Wave, given wavespeed, wavelength, amplitude - find w.

What I chose to do was analyze what happened at x=0. At x=0 I know sin of whatever will be 0. So 0=sin(kx-wt) and since x=0, w=Arcsin(0)/t. But this doesn't make sense because the answer isn't 0, its 0.695.
43. ### Damped Oscillation Amplitude Decrease vs. Mass Relationship

so what I did was e^-(1/10.1)=0.9057 and e^-(1/14.8)=0.93466 Then 0.93466/0.9057 = 1.03198, so the heavier mass dampens 1.03 times more than the lighter mass. If the lighter mass decreases the oscillation to 72.1%, then the heavier mass would be 72.1%*1.03198 = 74.4, but this is wrong. It...
44. ### I Is there an uncertainty between amplitude and phase in an EM wave?

Is there an uncertainty between amplitude and phase in classical quasi-monochromatic light?(E(t)=a(t)cos(phi(t)-omega_0*t))If it exist, what is the relation between classical and quantum uncertainty(delta I* delta phi>=1/2)?
45. ### Can heavy objects be used to modulate light waves with small amplitude?

Question: Can heavy objects be used to operate light waves with smaller amplitude, or waves with high amplitude be used to operate objects with small mass? This is a diagram I drew that illustrates my point. Heavy objects are meant to be celestial bodies, and the light source generates a beam...
46. ### MHB Affect of mass on amplitude

I'm working on a forced single-degree-of-freedom (SDOF) oscillator. I'm trying to find how an increase in mass will affect the response amplitude? I'm looking for mathematical proof explaining this reduction in amplitude. How to derive \delta x
47. ### Calculating Wave Amplitude and Frequency

My attempts were these, a) 2.0% / cycle * 25 cycles = 50% So, I got half of the first amplitude which is 0.5 m (seems not right though...) b) w=2pi/T , so put 0.5 at T, I got w=12.6 cycle/sec 12.6 cycle / sec * 6.3 sec = 79.2 cycles and it is obviously not right to me... May I get...
48. ### Calculating the amplitude of waves in water

Suppose I have a perfectly circular pool which is four meters in radius, two meters in depth, and filled with water. Say I drop a steel ball with a radius of five centimeters into the middle of the pool from a height of five meters above the water's surface. After three seconds, what will be the...
49. ### New amplitude of a spring-mass system when a 2nd mass falls on the first

I am confused about conservation of momentum for this question. I take the system as two objects, each having mass m. For first object (the one performing simple harmonic motion), there is net external force acting on it in horizontal direction (restoring force of spring). For second object...
50. ### I Calculating 2nd Order Scattering Amplitude: Feynman Diagrams

In the following I will try to deduce the scattering amplitude for a specific interaction. My question is at the bottom, the entire rest is my reasoning to explain how I came to the results I present. My working Let's assume I would like to calculate the second order scattering amplitude in ##...