# What is Beams: Definition and 274 Discussions

Beams is a Japanese clothing brand, established in 1976 in Harajuku district of Tokyo, whose chief executive officer (CEO) is Yo Shitara. The brand has stores in Japan, and branch offices in New York, Milan, London, and Paris.

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1. ### I Generation of polarization-squeezed beams

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...
2. ### I Understanding Scattered Radiation in Photon Beams

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...
3. ### I Grating Resolving Power of Laser Beams with Gaussian Distribution

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...
4. ### Cylinder Force Calculations

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...
5. ### B Sagnac effect for matter beams

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...
6. ### B What happens when 2 beams of light interact?

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.
7. ### Calculate Deflection for Aluminium Tube Beam - Inertia, Mass & δ

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...
8. ### I Do Photons Attract Each Other?

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...
9. ### I Queries on the operation of the LHC with pilot beams before Run 3

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...
10. ### A Slowing down molecular beams

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...
11. ### Engineering Solving Stresses in Beams: Reactions at B & F

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...
12. ### Allowable uniform loads - W beams vs. LVL

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...
13. ### B Relative speed of two oppositely directed light beams

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...
14. ### Engineering BMD of 4 beams joined at an intersection

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...
15. ### Engineering Where are fixed beams used in real life?

where are fixed beams used in real life? having real trouble googling them ad finding examples apart from buildings.
16. ### Engineering Maximize Structural Stability with Fixed Beams: A Guide to Their Application"

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...
17. ### Engineering Moments at the connections between a horizontal beam and the 3 vertical beams supporting it

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...
18. ### Bending proton beams under magnetic field

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...
19. ### Engineering Cantilever and encastré beams: bending moment and shear force

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...
20. ### Why can't two laser beams from two sources Interfere if they have a difference phase?

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...
21. ### I What powers the quasar magnetic beams that power jets?

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...
22. ### What's the direction of electric field in Laguerre-Gaussian beams?

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.
23. ### Can I Transform Multiple Steel Beams into a Single Piece of Concrete?

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...
24. ### I Will anti-parallel light beams between two stars stay parallel?

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...
25. ### Laser beams interacting with a screen | AM and momentum conservation

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...
26. ### Shear Stress Distribution Along a Beam

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...
27. ### What is the magnetic field generated by these two particle beams?

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...
28. ### B Measuring Michelson–Morley light beams

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...
29. ### A Phase Space and Its Use in Monte Carlo Simulations of Radiation Beams

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...
30. ### Overlaying light beams by one replacing the other where they intersect

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...
31. ### Two parallel opposed Co-60 Gamma Ray beams in Excel

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...
32. ### Advantages of Hermite-Gaussian beams?

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

### Force between two charged particle beams -- proton and electron beams

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...
34. ### Resolving reactant forces on supported beams.

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...
35. ### A Why light beams attract or repel each other even when they don't have charge

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
36. ### Castigaliano's Theorem for cantilever beams

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...
37. ### Determining Acceleration of Hinge in a Beam and Hinge Structure

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...
38. ### B Pulsar Beams: Spin, Wobble, & Projection

Is the beam of a pulsar projected perpendicular to its spin? If so, is the "pulse" due to wobble?
39. ### B Light Beams Attraction: e=mc^2 & Asymmetry

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...
40. ### Vibrations in cantilever beams

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...
41. ### Superconductivity for light beams?

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?
42. ### Framework Problem: Constructing Engine Mount for Airplane

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...
43. ### Calculating Beam Sizing for Cargo Transport

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...
44. ### Draw the shear force and bending moment diagrams for beams

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...
45. ### Compression/Tension in Steel I Beams

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...
46. ### B Can Different Wavelengths Affect the Gravity Between Light Beams?

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 ?
47. ### A Multi Gaussian beams explanation

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!
48. ### I What happens when two light beams approach each other.

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...
49. ### Max Bending Stress: Find from Second Moment of Area

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...
50. ### Einstein Coefficients - Laser Beams

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...