Propagation Definition and 487 Threads

Homework Statement: Propagation of Error for Focal Length Homework Equations: f = (s'*s) / (s' + s) In my lab, we had to calculate the focal length of a lens based on object distances (s) and image distances (s') that we measured. The object distances were measured with an uncertainty of...

Hey everybody, Background: I'm currently working on a toy model for my master thesis, the massless Klein-Gordon equation in a rotating static Kerr-Schild metric. The partial differential equations are (see http://arxiv.org/abs/1705.01071, equation 27, with V'=0): $$ \partial_t\phi =...

Homework Statement: Physics Lab Propagation of Error Issue Homework Equations: ∂f/∂b=∂/∂b (tan^(-1)⁡(a/4b))= 1/(1+(a/4b)^2 )×(-a)/(4b^2 )=1/(1+((5.922 cm)/(4×1.766 cm))^2 )×(-5.922 cm)/(4×(1.766 cm)^2 ) Hello, I'm trying to find the uncertainty in a function from the lab manual for the...

Summary: Robert Sungenis explains the sagnac effect Robert Sungenis, a well-known proponent of geocentrism, has authored a https://gwwdvd.com/what-allows-the-sun-to-revolve-around-the-earth/ in which he tries to explain the Sagnac effect as a result of Coriolis force (p.16-17), which he thinks...

I have a proton and an electron at a certain distance from it. The proton exerts an electrostatic force on the electron. I then neutralize the proton's charge by firing another electron at it from behind. How long does it take for the first electron to sense the change?

If I write ##f=\frac{uv}{u+v}## and then take differentials on both sides, I get ##\frac{df}{f}=\frac{du}{u}+\frac{dv}{v}+\frac{du+dv}{u+v}##, I get the fractional error as 0.03. (I have replaced the negative signs that come as a result of quotient rule with positive signs, since we are asked to...

I uploaded the paper from Belden cable company. It said the velocity slows down to 5EE6 m/sec from 1EE8 m/sec at RF speed. I don't remember I ever read this before, I thought velocity = 1/sqrt( μ/ε). Please give me a link on the reason if this is true. Thanks Alan

Homework Statement The following may appear to be a rather strange question but I have no access to a lab to conduct experiments so I have to rely on my imagination, and questions from textbooks, to contrive questions that will hopefully improve my understanding of a topic. I have recently...

I thought gravitational waves were how changes in the gravitational field was propagated. The Insight https://www.physicsforums.com/insights/how-fast-do-changes-in-the-gravitational-field-propagate/ says so as well. What got me confused was the following scenario: take a stationary black hole...

I've wondered this for a while but not known how to ask the question, If light is a transverse wave, then what is it transverse to? To elaborate, light travels in three-dimensions, radially. To me, this seems analogous to the sound wave, with pulses of pressure moving longitudinally to the...

Homework Statement An object of mass m=2.3±0.1kg moves at a speed of v=1.25±0.03m/s. Calculate the kinetic energy (K=1/2mv2) of the object and estimate the uncertainty δK? Homework Equations - Addition error propagation--> z = x + y and the Limit error--> δz = δx + δy -...

Ok so I drew up something (I know its horrible), but is this correct? Does the black line in the middle represent the propagation of the photon? If this is correct I would like to know and anything else that could help me or just anything related to this.

We know that skin depth in a conductor is found using the following expression, (Credits: http://farside.ph.utexas.edu/teaching/315/Waves/node65.html) Basically, as the wave propagates in a conductor, it's electric field strength reduces and reaches 1/e of it's initial value at the skin depth...

Hey there, First time on this forums, looking forward to some interesting discussions :) I am currently trying grasp the concepts of error propagation and standard deviation in relation to experimental physics. I have some data set and i want to determine the difference between the measured and...

I'm doing a lab report from electronic spectrum of iodine. I did Birge-Sponer plot from my data. Excel gave it to me a slope y = -2,0698x+133,34. From regression analysis I get uncertainties for slope and intercept. Slope: ##-2,069761731 \pm 0,075075941## Intercept: ##133,3385857 \pm...

Hello again Physics Forums! I have a question about fluid dynamics. Perhaps someone here can help me out. I am trying to understand how a plume of water moving at some speed carries momentum within a body of water. For instance the ‘exhaust’ from a submarine propeller. I am having a hard time...

When light enters an ocean, the photons scatter elastic with water molecules yet the presence of opaque particles causes the depth to be limited. Is this scattering Rayleigh scattering? (like the scattering in our atmosphere) https://en.wikipedia.org/wiki/Rayleigh_scattering

Homework Statement Light of free-space wavelength λ0 = 0.87 μm is guided by a thin planar film of thickness d = 3.0 μm and refractive index n1 = 1.6, surrounded by a medium of refractive index n2 = 1.4 critical angle = 61.04° n0 = 1.00 (a) Determine (i) the angle of incidence θ and (ii) the...

Homework Statement Use Maxwell's equations to elaborate an coherent explication of why electromagnetic waves propagate independently of the source that produces them. Homework Equations Maxwell's equations in vacuum: ##\nabla * E=0## ##\nabla * B=0## ##\nabla \times E = -\frac{\partial...

Homework Statement 2) A student is performing an angry bird experiment in real life. He calculates the range of the projectile by shooting the bird with a 30 degree angle and an initial velocity of v0 = 20 m/s. a) If the relative accuracy of setting the projectile angle is delta theta/theta =...

I noticed HF radio waves travel farther and easier when the sun is out rather then during the night. Why?

What I've read on the Michelson/Morley experiment explains that it made the idea of the luminiferous aether seem less likely, but I don't think I've ever seen an explanation of why everyone didn't just assume that light follows normal Newtonian relativity. What I mean is this: according to...

What actually is a mode of optical fiber propagation?Is it similar to modes which correspond to various configurations as in standing waves on a string ? Also How correct is it to consider no. of rays as no of modes?

Homework Statement [/B] So basically I am calculating the terminal velocity for a small sphere falling in a measuring cylinder filled with glycerine. The distance traveled is 20 cm (0.20 m), and I have conducted 3 trials for each temperature. I have measured the displacement of the ball using...

This is an issue I've seen asked and answered before on this forum some years ago. However, the answer doesn't quite make sense to me, so I want to see if I can get either a more satisfactory answer or a better explanation of the original. Suppose that I have some cells that produce a...

Homework Statement A horizontal string at tension T is tapped at the midpoint to create a small transverse pulse. What happens to the pulse as time passes? If the pulse is instead created at a point other than the midpoint, what happens to it? Neglect damping. Homework Equations Speed of...

Hi. Reading some recent threads I have found basic questions about light, fields, etc. For example, why something like light, associated with the electric and magnetic fields, can exist in a vacuum. And I noticed that every time I've been asked that kind of question, I answered "how" the...

Hello, Many Researchers talked about the following parameters: 1. Propagation length of the surface plasma wave(spw). 2. penetration depth of surface plasma wave(spw). 3. concentration of the (spw). 4. the equation of the interface in vacuum - plasma interface. I feel confused regarding such...

Homework Statement I have an empty cylinder with an external diameter of (23.0 ± 0.5) mm, an internal diameter of (22.5 ± 0.5) mm and a height of (60.0 ± 0.5) mm. I need to calculate its volume with its uncertainty/error. Homework Equations The Attempt at a Solution I do it like this...

Homework Statement Some Background - We are calculating the amount of acetylsalicylic acid in a sample using spectrophotometry. We were told to make sure to include the error in our answer. So first to calculate the moles of acetylsalicylic acid in a measured mass. 0.1620 ± 0.0005g measured...

i have an equation like this: Given m(B-V)= 1.2 +- 0.2 How do you calculate the uncertainty in T? (btw, I solve T using graphs by finding the intersection point) My idea was first to calculate T when m(B-V) =0.2, and I then calculate T when m(B-V)= 1.2 + 0.2(its uncertainty). and then find the...

How is it possible for different parts of a single rectangular wavefront to produce different intensity at particular point(P) despite the fact that wavefront is something which has all the particles at same phase?

Hello everybody! For my water in nanoscaled-pores simulations with SPH I need a value for the characteristic velocity. My planned approach is to estimate this value by attaining the propagation speed of a diffusion wave. But I have problems with understanding this process since I find some...

Homework Statement Given the following expression $$ \Psi(x,t) = A cosh(36 x^2 - 12 x t + t^2)$$ Determine whether this is a traveling wave and if so what is its propagation velocity and propagation direction? Homework Equations Wave equation $$ \frac {\delta^2 \Psi(x,t)} {\delta x^2} =...

Hello everyone, I'd ask you through an illustration which for me would be more clear to put questions I wrote in the image: Thanks to all! Cheers Luigi

If someone has used the python program POPPY, I'd like some help. How can I set up two wavefronts entering at slightly different angles, and then see the interference pattern?

Homework Statement An E field with f = 2.45*10^9 Hz passes through a material with the following properties e_r = 10 u_r = 1 sigma = 1 (S/m) The Incident E field has peak magnitude of 300 V/m at the air to surface boundary. (a) *solved* Find the incident power density at the material...

The Sun, mass decreases as energy increases, i.e. 2 x hydrogen = 1 x helium ( less a little bit = a photon ) until it is ultimately swalled up by a black whole, a magnet with strong force, a ball of iron? am I on the right lines ?

Hello! I have been thinking of broadcasting a message into outer space. It sounds silly, I know, but that's just something I'd like to do for and with my niece. She's 8 years old and very interested in physics (as far as she understands it). I have some knowledge in electronics, I think I...

Homework Statement given E is constant, find the uncertainty in the angular frequency, ω. can someone please check my work? Homework EquationsThe Attempt at a Solution

http://imgur.com/cUNs2z7 In this book I found by chance on Google, the author claims that “solutions of the wave equation only take the form of functions (...) in one and three dimensions. In two dimensions solutions are more complex”. Then, at the end of the paragraph of interest (which I...

Hello Please help me, my function is; alpha = [ i1.g2 / (i2.g1) - 1 ] / ( t1-t2 ) I will have to measure i1, i2, g1, g2, t1 and t2 them I made classical error porpagation, but I don't know if this is ok. How is the proper way to calculate the propagation error for alpha?

Hey guys, I'm in a class where we're learning about waveguides, and without going into too much depth, we often solve an equation $$ \tan{(\kappa (\frac{a}{2}))} = \frac{\gamma}{\kappa} $$ for ##\kappa## numerically since there isn't an analytic solution for ##\kappa##. I'm doing a project...

Hey, I'm trying to propagate my percentage errors through some hefty equations and come up on a bit of snag: I've got a percentage error for x and know how to deal with it for trig functions and powers, however since both errors are from the same source: y = sin(x)^2 / x^2 Should I just...

Is there any theory to say if expansion started with a finite seed and propagated out at a finite speed vs somehow happening everywhere at once? I know the layman's phrasing is that expansion happened everywhere at the same time. That might just mean that the very small part of the early...

If $$\phi(t,x)$$ is a solution to the one dimensional wave equation and if the initial conditions $$\phi(0,x) , \phi_t(0,x)$$ are given, D'Alembert's Formula gives $$\phi(t,x)= \frac 12[ \phi(0,x-ct)+ \phi(0,x+ct) ]+ \frac1{2c} \int_{x-ct}^{x+ct} \phi_t(0,y)dy . \tag{1}$$ which is...

Hi all, (See attached image file) Two mutually coherent and collimated light beams intersect as shown, creating the stationary 'bright' and 'dark' fringes of fig.A. Suppose that, after the fringe pattern has formed, we insert a very thin (compared to the fringe-width) and (ideally) perfectly...

Let's say we have a 3 floor/level building , and someone is making noise outside, i.e: Playing guitar, given that all the building has the same sound isolation everywhere, what can you say about the sound propagation? we have 2 cases a) when windows opened b) when windows closed Will the...

Hello! Can someone explain to me the physical meaning of ##\bar{\psi}=\psi^\dagger\gamma^0## in the Dirac equation? For example when calculating propagation amplitude I see that what we calculate is ##<0|\psi(x)\bar{\psi(y)}|0>## and not ##<0|\psi(x)\psi(y)|0>## (as we do for KG equation) and I...

I am working on a project which consists in calculating numerically the trajectory of a light ray in the Friedmann-Lemaitre metric with the case "k = 0" (euclidean space) and zero cosmological constant. The light ray is emitted by a source galaxy at instant ##t_{0}=\dfrac{2}{3H_{0}}## (today)...