Amplitude Definition and 825 Threads

In the amplitude modulation equation, V=(Ec+Ei*coswt)coswt I don't understand why the instantaneous value of information signal is used. Shouldnt it be peak value as that would give the maximum value (amplitude)?

Does it make sense to talk about the amplitude of a photon? In my mind, the amplitude of the photon is the maximum strength that the electric and magnetic field gets as they oscillate. If you were to change the amplitude of a photon (say increase), then the maximum strength of the e&m fields...

Homework Statement Given that the scattering amplitude off of a single atom is f_{1}(\vec{q}), find the scattering amplitude for 1) four atoms each placed in the corner of a square of length a, and 2) two atoms a distance d apart Homework Equations The total scattering amplitude can...

Hi all Homework Statement I have the first three states of the harmonic oscillator, and I need to know the amplitudes for the states after the potential is dropped.Homework Equations u_{0}=(\frac{1}{\pi a^{2}})^{\frac{1}{4}} e^{{\frac{-x^2}{2a^2}}} u_{1}=(\frac{4}{\pi})^{\frac{1}{4}}...

Homework Statement A sensor yields a signal y(t) = |sin(120\pit)| a. Using Fourier analysis please construct an amplitude spectrum for this signal. Homework Equations A0 = \frac{1}{T}\int ^{-T/2}_{T/2}y(t) dt An =\frac{2}{T}\int^{-T/2}_{T/2}y(t)cos\frac{2n\pi t}{T}dt The Attempt at...

i am looking for the amplitude ratio and phase shift of this graph? could someone explain me how to obtain these results from this type of graph? thank you

Hello and thanks for you time. Just a quicky :-) For a free vibration impulse response, the acceleration a is given by: a = -ω^2*Asin(ωt) So am I right in saying that you can rearrnage to calculate the amplitude A as: A = a/(-ω^2*sin(ωt)) Thanks, Steve

Is amplitude in a simple pendulum measured as an angle, theta, or as a distance? If it is an angle, is it in radians or degrees. Also, what is the equation? How does amplitude relate to x=Acos(ωt)?

Gamma ray can use to kill tumour because of higher frequency and therefore higher energy. The energy here is the number of time of the wave hit on the tumor or the amplitude of wave ? Thank you.

Hi, I would like to understand how diffraction works in layman's terms. Why does a wave entering a corner or a slit (in the case of light) bend? I found an answer here, but it doesn't make a lick of sense. http://wiki.answers.com/Q/How_does_diffraction_work What is a probability...

Homework Statement See attached image Homework Equations Δphi = 2pi(Δx/λ) + Δphi0 = 2pi(m) -- at the maximum Δphi = (m + .5) (2pi) -- at the minimum The Attempt at a Solution The first step should be to solve for lambda, the wavelength. So I plug in the knowns: At 30 cm...

Homework Statement I need to give scattering amplitude f(θ) in Born approximation to the first order in the case of delta function scattering potential δ(r). The problem is in spherical coordinate and I'll give major equation concerned.Homework Equations The equation for scattering amplitude is...

Homework Statement The question is "Comment on the physical consequence of two probability distributions being equal to each other even though the probability amplitudes are not the same." Homework Equations The Attempt at a Solution I understand that the modulus squared of the...

Homework Statement An oscillating system of a block attached to a string where k = 400 at some time t has a position x of 0.1 m, velocity of -13.6 m/s, and accel. of -123 m/s^2. Find the amplitude of the motion. Do not use energy. Homework Equations x = Acos(wt + phi) v = -Awsin(wt +...

A harmonic wave traveling in +x-direction has, at t = 0, a displacement of 13 units at x = 0 and a displacement of -7.5 units at x = 3λ/4. Write the equation for the wave at t = 0. Homework Equations The equation for a harmonic wave is r = asin(kx-vt+θ) a being the amplitude k...

Homework Statement A mass is attached to the wall by a spring of constant k. When the spring is at its natural length, the mass is given a certain initial velocity, resulting in oscillations of amplitude A. If the spring is replaced by a spring of constant 2k, and the mass is given the same...

Hello all, (Newbie here so I hope I'm posting this in the right section, if not please guide me to the correct one) I'm studying Hooke's Law in Physics and there is something I can't understand. The equation for the Simple Harmonic Motion of a spring is given by x'' + wx =0 the general...

Homework Statement See attached screenshot Homework Equations Vmax=Aω ay=-ω2A The Attempt at a Solution The given max velocity is 1.2 m/s, so 1.2 = ωA Ay = -ω^2A 1.2/A = -√260/A A = 0.005

Homework Statement Original question: A boy flicked a string harder, describe the changes of the waveform and the speed of the wave. Homework Equations V = f x λ Frequency is how many completed oscillation per second. Wavelength is distance between two adjacent points of the same...

Homework Statement The scattering amplidtude, F, of a, by a crystal, diffracted beam is defined to be: (1) F=\sum{_\vec{G}}\int n_{\vec{G}}e^{i(\vec{G}-\delta\vec{k})\cdot \vec{r}}\mathrm{d}V The integral is over all the volumeelements, dV, of the crystal. n_{\vec{G}} is the local...

I would like to calculate the power of a beam of light once I know the electric field amplitude. For example if I know the amplitude along a line from -1 meter to +1 meter every 0.5 m is [1, 2, 2.5, 2, 1 V/m], how can I find the power from this is? Is there enough info? (it's in vacuum/air)...

Lagrangian I have is little bit massy so I don't write in here. Like in ψψ(dagger) , or ψ∅ -> ψ∅, How can I calculate the differential cross section or total, or amplitudes?

So if Period is the only thing that isn't dependent on amplitude, then that must mean Energy (PE = 1/2 k A2), maximum acceleration, and speed is dependent on amplitude?

How do you find the force extended if given the amplitude? Is main questions, I also have one slight question. Ok, doing a problem. There is no damping. A (.15kg) object is hanging from a light(6.30N/m) spring. A sinusoidal force with an amp of 1.7 N drives the system. And the problem is...

I cannot see why the probaability ampltiude for an initial state to turn into another state is the inner product between the "another state" and the propogator acting on the initial state, since this is just equivalent to the inner product between the "another state" and the evolved initial...

Lets say we have a weight attached to a spring. When releasing it under water (whole motion occours under water) at different initial amplitudes, will logarithmic decrement be the same? And will the period change? I think it should be the same for different initial amplitudes. But...

Hello again, My question is on determining the scattering amplitude via time-dependent perturbation theory (first-order) for a given potential - I believe the perturbation potential is modeled due to some interaction between two scalar particles and has form: \delta V=\lambda...

Homework Statement Suppose sound wave is emitted uniformly in all directions by a speaker. At a distance of 1.1m, the amplitude of it sound is 1.2x10^-8m What is the amplitude of sound at a distance of 1.7m?The Attempt at a Solution What I'm confused is why does the amplitude of sound change...

The circuit in the figure is driven by a 9 mV amplitude signal generator with an output impedance of 2 kΩ. What is the output voltage amplitude from the amplifier? So what I did basically is use the formula Vout = -R2/R1 x Vin So.. I know Vin is 0.9 V (9mv) and R2 = 12 R1 = 1 that...

Lets take visible light for example. The frequency/wavelength determines the amount of energy and the type of wave(micro,radio,gamma ect.) The intensity or brightness is determined by the amount of photons. So what does the amplitude determine?

In my textbook, when two waves of the form: y_1 = A\cos \left( 2\pi f_1t \right) y_2 = A\cos \left( 2\pi f_2t \right) combine, the following trig identity is used: \cos a + \cos b = 2\cos \left( \dfrac{a-b}{2} \right) \cos \left( \dfrac{a+b}{2} \right) which yields an expression for y...

My book discusses the oscillations of systems for small pertubations around an equilibrium point. By considering taylors expansions of the potential and kinetic energy they are led to a set of equations for the amplitude factors. I have attached the crucial lines as a picture. My question is...

Hi Let's stick to the classical limit. We have 2 monochromatic light waves of same intensity. Let's say one is blue and one is red. Now this means the individual photons of the blue light have more energy(obviously, higher frequency) and the red light photons have lower energy. But since...

Homework Statement The wavefunction of a transverse sinusoidal wave on a string has the form y(x,t) = Acos(kx + ωt + φ), where x and y are in m, t is in seconds and φ is the phase constant in radians. The wave has a period T = 24.5 ms and travels in the negative x direction with a speed of...

Suppose you run an AC-current through an RC-circuit. Writing it all up in terms of the complex impedance you find that the current amplitude is decreased due to the capacitor. Physically I do not understand this. How does a capacitor decrease the amplitude of the current, when the current is...

The problem statement Sketch the Amp spectrum of the following... Additionally, for x3, sketch the phase spectrum... ( j is the imaginary number) x1(t) = cos(10pi*t) + cos(3pi*t) x2(t) = cos(10pi*t) + cos(5pi*t) - j*sin(10pi*t) x3(t) = cos(10pi*t + (pi/6)) + j*sin(10pi*t) The...

Homework Statement A block rides on a piston that is moving vertically with simple harmonic motion. (a) If the SHM has period 2.65 s, at what amplitude of motion will the block and piston separate? Homework Equations x(t)=xmcos(ωt + ∅) a(t)=-w2xmcos(ωt + ∅) Where xm is the amplitude...

Q: A single sinusoidal signal is found in a large amount of noise. If the RMS value of the noise is 0.5 volts and the SNR is 10 dB, what is the RMS amplitude of the sinusoid? I've related the question to the following equation: SNR=20log(singal/noise)dB My answer is 1.58 volts, BUT I'm...

Hello Everyone! About Amplitude Modulation, Usually it is seen in the book or web that (e.g. http://www.ni.com/white-paper/3002/en ) '''' The message signal can be represented by m(t) = Mb cos(2πfb + φ) and the carrier signal can be represented by c(t) = Ac cos(2πfc + φ), Now...

Homework Statement Transparent wax of refractive index n=1.3 is deposited on top of a glass plate of width 1cm and refractive index n=1.5. The thickness of the wax is 0.01mm at one end of the plate and tapers uniformly to zero at the other end of the plate, which is defined to be at x=0. At...

Hi, For an undamped mass, spring system subject to a harmonic force, the equation is: ma+kx=Fsin(ωt) where a=d^2/dx^2 After solving the diff eqns, the steady state amplitude is: X=(F/m)/(ω^2-ω0^2) where ω is the frequency and ω0 is the natural frequency =sqrt(k/m) according to the...

Hello all! I am trying to understand ER on a more intuitive level. I can see the relationship between energy and frequency. The relationship between amplitude and photon number is less clear. So far I have E = hf. I understand that the intensity of light is a function of the number of...

Homework Statement A sheet of glass transmit 70% of the energy of the incident light What is the value of the quantity: (Amplitude of transmitted light) / (Amplitude of incident light) A:0.49 B:0.70 C:0.84 D:1.19 Homework Equations Intensity is proportional to amplitude square...

1. If the incident wave is coming from LHS, what happens to the wave amplitude on the RHS when electron energy is equal V0? 2. the wavevectors on both sides of the step are different (generally), is there an energy at which the have the same magnitude? thanks for any help..

(1) A mass of 3.0 kg is suspended from a vertical spring and produces a static deflection of 60 mm. The system is also subjected to viscous damping of 36 N s/m. Calculate the value of the: (a) natural frequency i. In Hz ii. And rad/s (b) damping ratio...

Hi I was reading Feynman's third book and I don't understand why, with bosons at low temperatures, 'there's more amplitude to go into the same state than into an unoccupied state by the famous factor √n, where n is the occupancy of the lowest state'. Thanks.

Is it possible to calculate the phase and signal amplitude from data gained from FFT? For instance, if I have a samples from a signal B+A*cos(ψ), is it possible to obtain A and ψ? Extra challenge: is it possible to do so without division? (I am looking to put this on a DSP and division is...

I read on a website that in amplitude modulation the actual carrier wave does not change its amplitude but rather the sidebands. Is this true

Hi, I am repeating first year exams and would really appreciate some help with my study. Just can't seem to get my head around this problem. Homework Statement Consider two identical ideal springs with a mass m attached which are harmonically oscillating out of phase relative to each...

Hello all, I have a vector, let's say A, which has measured values of the Earth's magnetic field (and if it is relevant, two vectors X and Y with the coordinates of the point each value was measured). I need to calculate the amplitude, phase and energy spectrum using FFT in MATLAB X...