Beams Definition and 274 Threads

Stokes operator squeezed continuous variable polarization states https://arxiv.org/pdf/quant-ph/0208103.pdf Polarization squeezing and continuous-variable polarization entanglement https://arxiv.org/ftp/quant-ph/papers/0108/0108098.pdf I just found out from these sources that beams of light...

Consider a source emitting a beam of photons. These photons pass through x thickness of material. The attenuation coefficient of the beam \mu is known. We can write this formula If I'm not wrong, this formula tells us the number of photons that passed through the material of thickness x...

All resources I’ve found for grating resolving power assume uniform distribution on the grating and produce airy disks. Resolvance is determined by the Rayleigh criterion where the peak of one wavelength is at the minima of the adjacent one. This definition doesn’t seem applicable for Gaussian...

I am trying to calculate the force required to lift/move the beam clockwise from the shown position. I have a force (F1) acting at the end of the beam, 5,000lbs pushing to the left, as shown. What is "Fcyl", or the force required by the cylinder to life the beam with the acting load, and rotate...

Hello, I have recently come across this article by Rizzi and Ruggiero, called "The Relativistic Sagnac Effect: Two Derivations": https://arxiv.org/pdf/gr-qc/0305084.pdf In section 3, the authors derive the Sagnac proper time difference for all beams (light beams and matter beams, including...

I realize turn into probably isn't the correct term. Also I know gravity can bend light but can gravity cause light to turn into other particles? I am layman so can someone explain this in layman's term? Also I am not even sure the quantum section is the correct section.

Hi There, I am wanting to calculate the amount of deflection (δ) from a simply supported Beam. My Beam is an Aluminium Tube ø30mm with a 3mm Wall Thickness. Force (F) - 500N Length (L) - 610mm Youngs Modulus (E) - 68 Gpa Moment of Inertia (I) - ? δ = F L³ ∕ 48 E I Q1: Is this the correct...

Then the equation of motion for a photon in the beam (moving parallel to the ##x## axis) is\begin{align*} \ddot{y} = - \Gamma^y_{\mu \nu} \dot{x}^{\mu} \dot{x}^{\nu} = -[\Gamma^y_{00} + \Gamma^y_{xx} + 2\Gamma^y_{0x}](\dot{x}^0)^2 \end{align*}and similar for ##z##. In the linearised theory...

We all are aware of the fact that the LHC is now seeing pilot beams in preparation for Run 3 next year. Recently, I came to know about a Twitter account, @lhcstatus2, which automatically posts updates about the current operation of the LHC. I am interested in learning about some of the different...

Hello! If I have a beam of positively (single) charged molecular ions (they can be either bunched on continuous), and I want to end up with a decelerated (close to stationary) ensemble of neutral molecules (e.g. to trap them in a MOT trap), is there a way to reduce the velocity of the charged...

To determine the reactions at B and F, I don't know how to handle that L-shaped beam connected to the horizontal beam. My attempt is: $$\sum F_{y} \colon\;\;\; -200 + R_{B} - 75 + 32 + R_{F} - 1632 = 0$$ from which it follows that ##R_{B} + R_{F} = 1875##. $$\sum M_{B} \colon\;\;\; -5 \times...

I'm trying to make a comparison between the maximum allowable uniform load of a beam made of steel vs LVL. Here is a table of allowable uniform loads for steel W beams: https://www.engineeringtoolbox.com/w-steel-beam-uniform-load-d_1722.html Here is a table of allowable uniform loads for LVL...

Can someone give a meaningful explanation that the relative speed of two oppositely directed light beams is why only one light speeds? I understand that based on the Einstein relativity theory, the relative speed of two beams is C, because nothing can be quicker than light speed. However it is...

4 beams are supported by the column at one side, another side is jointed together at the intersection. I have assigned UDL of 20 kN/m on all the beams. 2 beams are longer (3m), 2 beams are shorter (2m) . Surprisingly, the BMD of the longer beams is hogging at the middle part , while the BMD of...

where are fixed beams used in real life? having real trouble googling them ad finding examples apart from buildings.

Hi Ive write about beams and on last one having bit of trouble finding stuff. Has anybody know where built in (encastre) beams are used. Ive write so far build in beams are beams that are fixed to a flat plane surface. Fixation provide high resistance to force applied (horzontial and...

Say that I have a continouos beam resting on top of column spanning across 3 column. The applied load is UDL on the beam, here's how the BMD look like. My question is whether the connection between the beam and column need to sustain the moment ? Which point need to sustain the moment ? All 3...

I haven't taken a physics courses in some time and I'm having trouble getting started with this textbook question. I know that there will be relativistic effects present, but I can deal with that. The problem is how I can approach the problem. I initially thought of a geometric way to set up...

I have to discuss the Bending moment and shear forces in cantilever and encastré beams. Does anybody know of good websites showing that is simple to understand showing. All i can find is how to calculate and bending moments and shear force digrams which don't really understand. Can...

I read in the internet that the reason that two laser can't Interference because they most likely have difference phase. but electromagnetic wave are just change in the electromagnetic filed that goes up and down , so mathematically they may Interference little let say that the there is...

I am reading up on quasars because I am interested in the magnetic beams that emanate from their poles, accelerating material. I read that the magnetic beams are generated by the orbiting debris the quasar is consuming. Sorry, that doesn't sound right to me. I assumed the black hole core is...

As for Laguerre-Gaussian beams, the direction of wave vector is helical, and how about the direction of electric field? I found that there was little literature mentioned this.

When I convert the steel beams to concrete, do I transform the several different beams into a single piece of concrete in order to do the calculations to find the second moment of area of the beam or do I transform each beam seperately into a concrete piece? Intuitively, t seems reasonable to...

In our galaxy, two stars, A and B, move about 20 km/s in slightly different directions to each other. The stars are about 15 light years apart. Initially, the light beams are exactly anti-parallel. Will light beams emitted from star A traveling towards light beams emitted from star B stay...

a) On the black part, all incoming light is absorbed. This means that the momentum of the left-light beam doesn't change (i.e. momentum before hitting the black screen is ##\vec p_0## and after hitting it is zero. Thus ##\Delta \vec p = \vec p_0##). If momentum doesn't change, we get no...

I know that shear stress in horizontal beams has a parabolic distribution, so that the max shear stress occurs at the neutral axis. I also understand that for a beam subject to a distributed load with supports at its ends, the magnitude of the shear force is highest at the left and right ends of...

A uniform beam of positively charged particles is moving with a constant velocity parallel to another beam of negatively charged particles moving with the same velocity but in opposite direction separated by a distance d. Then, how should be the variation of magnetic field B along a...

I was away for a few months and thought I might pose this thought I am working on, on this forum when I return. There was a very help full person who assisted me in the finer explanation of the Lorenz transformation a few months ago, and I really learned a lot about SR and GR. A few weeks ago, I...

In the field of medical physics, specifically in monte carlo simulation of radiation beams produced by electron accelerators, people call ‘phase space’ to a file that contains the data of a large number of particles when they traverse a reference surface in the machine (usually a plane), i.e...

Need to overlay beams by having one replacing the other where they intersect rather than have the beams be superimposed. this is what I want: https://i.imgur.com/F6HIYBl.png this is what I do not want: https://i.imgur.com/ylhMeEa.png This kind of beam combining can be either achieved by the...

Hi everyone, I have this question about POP. Assume a patient separation of 20cm. Using data for 6MV , FS 10x10 cm, plot the depth dose for one beam at 2 cm intervals. Include on your plot the dose at dmax and the dose at 20-dmax. On the same graph repeat this for the opposed beam. Now plot the...

And areas of usage? I will be glad if you help me.

Homework Statement A proton beam is going from north to south and an electron beam is going from south to north, so in which direction is the electron beam deflected Homework EquationsThe Attempt at a Solution . [/B] I thought an electron...

The questions States. A uniform plank of weight 120N rests on two stools. a weight of 80N is placed on the plank, midway between the stools calculate A) the force acting on stool A B) the force acting on stool B (Cant add a picture for some reason.) Plank over length = 4.0m from left hand...

Hi, Can someone please explain as to why light beams attract or repel each other even when they don't have charge. Seems like it behaves like two current carrying parallel wires. There is very little material about this which goes completely above the head. Thanks

Homework Statement Hi I am trying to derive an expression for the deflection in a cantilever beam using castigliano's theorem. I have found and attached an example of the solution. I understand the most of what is going on in the attached solution but I don't know where the b^3 came from in the...

Homework Statement The following structure,A force F is applied to the right hinge.If the mass of the rods are equal ,and the length of the rod is equal,the intial angle is also equal to 90 degrees (a square),What is the intial acceleration of leftmost hinge ? Homework Equations Coordinate...

Is the beam of a pulsar projected perpendicular to its spin? If so, is the "pulse" due to wobble?

Appearently, two beams of light in a vacuum are attracted to each other. Photons have no Newtonian mass, but their relativistic mass (e=mc^2 or mass-energy equivalence) causes this (as is my understanding). So will a 10^4 Hz beam bend more towards a 10^20 Hz beam than the 10^20 Hz bends towards...

Hi fellow mechanical engineers, I am designing a rather simple excel program for work that deals with vibrations in robots. Imagine a robot that is made up of linear axes that can move in x,y,z sort of like a 3D printer, take a look at this picture: https://pasteboard.co/8hvV5vf.png Focusing...

As is well known, superconductivity is described as a property of zero-resistance for electrical current, however, I want to know, is there any material with superconductivity for light beams, in which the light beams can propagate with no losses?

Hi! I'm currently doing a project where I'm constructing a framework for an engine mount connecting an airplane with an engine. The project involves both calculations by hand and with CAD(Creo), and i have no problem with the CAD part as i have done the simulations. The part with doing...

Good Day Guys, I need help in checking the beam size required to transport a cargo. What checks do i do? 1. Check actual BM with resisting moment of the beam 2. Check actual shear with the resisting moment of the beam How do i calculate following if I only know the type of beam used, i.e...

Homework Statement Homework Equations [/B] Shear force is calculated at each point on the beam. Downward forces are negative, upward forces are positive. Moments about points are calculated as force multiplied by perpendicular distance. Clockwise moments are negative. Anti clockwise...

Homework Statement Why is a steel beam shaped in the form of the letter "I" still strong enough to bear a load? 1) Its compression area is located on the top of the I beam. 2) Its tension area is located on the top of the I beam. 3) Its neutral area is located on the top of the I beam. 4) Its...

In the experiment using pencils of light by Tolman, is has been shown that two parallel light beams do not attract but anti parallel beams do. What happens if we use different wavelengths for the light beams. Will the higher frequency beam be less deflected ?

Can anyone explain intuitively or give a better explanation of multi gaussian beams and the ABCD matrix approach for sound (ultrasonics) and not light? Thanks!

Hello. Suppose there are two objects that are traveling at the speed of light, and that the observer is in an inertial frame of reference. These two objects are say, a light-second apart, and are approaching each other. From the frame of the observer, each object covers half a light-second...

Homework Statement The second moment of area of the beam shown about the neutral axis X X is 4x10^6mm^4 Find the maximum bending stresses, tensile and compressive, set up in a beam of this section 2.6m long and simply supported at its ends and carrying a concentrated load of 4.8kn at its mid...

Homework Statement Assume a two level laser system with no degeneracy (g1 = g2 = 1). If [tex]N_2 + N1 = \text{constant}[\tex], show that [tex]B12 = B21[\tex]. Homework Equations [tex]\frac{\partial N_1}{\partial t}=-B_{12}\rho(v_{21}N_1[\tex] [tex]\frac{\partial N_2}{\partial...