Diagrams Definition and 689 Threads

A diagram is a symbolic representation of information using visualization techniques. Diagrams have been used since ancient times on walls of caves, but became more prevalent during the Enlightenment. Sometimes, the technique uses a three-dimensional visualization which is then projected onto a two-dimensional surface. The word graph is sometimes used as a synonym for diagram.

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  1. Demon117

    Significance of Order in Feynman Diagrams

    I've been doing some review of particle physics in Griffiths and I came across this statement that really didn't stand out to me before. "the idea is to draw all the diagrams contributing to the process in question (up to a desired order), calculate the amplitude (M) for each one, and add...
  2. M

    Characteristics of Feynman diagrams for correlators at a given order of lambda

    I've been given an action of S = -\frac{1}{2}m^2\phi^2 - \frac{\lambda}{3!}\phi^3 and the question then require drawing the feynman diagrams for the <\phi\phi> at order \lambda^2. I am told that there are 2 connected diagrams at one-loop order and one disconnected two-loop diagram and...
  3. Hercuflea

    Thermodynamics - Help me understand phase diagrams

    Homework Statement So my thermo professor has been putting a huge emphasis on phase diagrams, which I didn't really expect. He basically skips most of the analytical/calculus type problems and gives us the graphical phase diagram/ "real world" type of problems for homework. I don't...
  4. G

    Trouble interpreting Bode diagrams

    Trying to get my head around frequency response and Bode plots, but I'm having trouble interpreting what's going on. The bode plot of a function is expressing what would happen to my function if I multiply it with sin(ωt), right? To get a better feel for it, I asked Matlab to give me the Bode...
  5. N

    Understanding Quark-Gluon Interactions: Deciphering Feynman Diagrams

    Hi all. I am new here but i decided to work a bit more and finish my diploma faster so i think i will use this forum more from now on. I was studing about quark color changes, quark interactions, gluons and generally the strong force. As i saw the Feynman diagrams i felt a bit confused...
  6. MalachiK

    What is the correct convention for anti-fermions in Feynman diagrams?

    Hi Guys. I'm hoping that you might be able to help me out with a question I have about anti-particles in Feynman diagrams. I'm drawing these again for the first time in over a decade because I'm teaching an elementary physics course that requires the students to draw diagrams for a few...
  7. N

    Desperate about Nyquist Diagrams

    Hi everyone! I searched all over the web and nobody/nothing gives a good explanation on how to plot nyquist diagrams... can somebody help with these ? I can't go forward in my study of control engineering without knowing these and I'm stucked... How are nyquist diagrams plotted starting from...
  8. Spinnor

    Feynman diagrams from Quarks and Leptons Halzen and Martin?

    Feynman diagrams from "Quarks and Leptons" Halzen and Martin? The following scan is from Quarks and Leptons: An Introductory Course in Modern Particle Physics, Francis Halzen (Author), Alan D. Martin (Author), page 9. Can I take anything from the topological difference between figure (b) and...
  9. G

    Changing the sign of 4-momenta in Feynman diagrams

    If a Feynman diagram only involves bosons, then can you multiply all external 4-momenta by negative one, and still get the same amplitude? Looking at the Feynman rules this seems true. If the diagram has a fermion (as real or virtual particle), then it seems this is no longer true. I just...
  10. M

    Create Feynman Diagrams online

    I need to put some Feynman Diagrams in a paper that I'm writing on my Mac (Lion) with Texpad, but I don't know how to create them in Latex (I tried it with some things I found on google [feynmf], but it didn't work). So I need a way to create them online, if you know one. I hope this is the...
  11. G

    Circuit Diagrams in Component Data Sheets

    What software is used by manufacturers to produce the thousands of data sheets for all of the products that they make? Specifically, the circuit diagrams which look very crisp, like they were made in a vector format. I assume that each manufacturer has some proprietary software that they use to...
  12. S

    Quark Flow diagrams - when is it Strong/EM/Weak?

    Homework Statement (1) Indicate whether the following process (if possible) occurs due to the strong, weak or electromagnetic interation. \pi^{-} p → \pi^{-} \pi^{+} n (3) Sketch Quark flow diagrams for the following, stating whether it's due to EM, weak or strong interaction; K^{*+} →...
  13. S

    What is a loop (in Feynman Diagrams)?

    Hey, I was wondering what exactly a loop is of this kind : I understand the initial & final four momentums to be the same and so there is no boundary on the possible allowed momentums in the loop. My professor said the loop is equal to (or can be modeled as) the self-interaction by...
  14. S

    Feynman diagrams and relativistic propagators

    Hey again, I have a question on a couple of things related to feynman diagrams but also the relativistic scalar propagator term. First of all, this interaction: The cross represents a self-interaction via the mass and characterised by the term: -im^2, is this just some initial state...
  15. G

    Can these diagrams describe an electrostatic field in a charge free space

    Homework Statement Determine if the following diagrams may describe an electrostatic field in a charge-free space. The rectangles are the spaces under consideration. In the first four diagrams there are field lines while in the last two there are equipotential lines Homework Equations...
  16. A

    Generating Shear and Bending Moment Diagrams for Beams with PDEs

    I'm trying to write a very simple program to generate shear and bending moment diagrams for beams. The thing is that I don't know what kind of loading that the beam may see so I want to be able to write it as generically as possible. I'm trying to find a web resource (not a book, unless...
  17. P

    Drawing Bifurcation diagrams for a dynamical system

    1. Homework Statement [/b] Consider the dynamical system \frac{dx}{dt}=rx-\frac{x}{1+x} where r>0 Draw the bifurcation diagram for this system. Homework Equations The Attempt at a Solution Well fixed points occur at x=0,\frac{1}{r}-1 and x=0 is stable for 0<r<1 and unstable for...
  18. L

    Free Body Diagrams: Easily Analysing Photos & Sketches

    Hi, When looking at a photo or sketch, I find it hard to take out the important bits and turn it into a freebody diagram. I am doing this question (pic attached). Im quite unsure how to even begin. I've though of a few ways to start analysing it. The first way analyses AD as a whole. And...
  19. B

    Help with finding missing quantities on Free-Body Diagrams

    Homework Statement Fill in the missing quantity for the following: V = constant FNet = ? a = ? F1 = ?Homework Equations FNet = Fn - Fg + Fa - FF Fg = mg FNet = maThe Attempt at a Solution Because I honestly do not know how to go about solving this, the only things I've done are review class...
  20. M

    Help Understanding Wiring Diagrams.

    Hello All, I was wondering if anyone can help me interpret these wiring schematics. As some know, I am trying to use a stepper motor to generate power. The motor can be wired in both unipolar and bipolar configurations. From my research, it seems to get the most power a Bipolar configuration...
  21. I

    Feynman diagrams for Quantum Gravity

    Dear collegues, I want to share with you a little idea which permits to obtain (almost apparently) renormalizable Feynman diagrams for General Relativity. (See attached file) This idea exchanges renormalizability with non-locality. I'll vary fain if someone of you will try to calculate any...
  22. E

    Statistical Mechanics: Phase Diagrams and Effusion

    Homework Statement There are two problems: The first problem is to calculate the slope of a phase-equilibrium line of a substance given its properties (Helium, Water, etc.) as the temperature approaches a certain value (in this case, T approaches zero). The second problem is the effusion of...
  23. X

    Static/Kinetic friction problem help (several problems - Diagrams included)

    PROBLEM 1 Homework Statement A block of mass m = 12.5 kg rests on an inclined plane with a coefficient of static friction of μs = 0.08 between the block and the plane. The inclined plane is L = 4.5 m long and it has a height of h = 3.25 m at its tallest point. m = 12.5 kg μs = 0.08 L = 4.5 m...
  24. J

    Attempt on Twin Paradox via Minkowski diagrams

    This is an attempt to solve the twin paradox via two Minkowski diagrams with a few questions attached. Note that there might be mistakes in this drawing i will fix in the course of this thread in case someone notices any. First, let me explain the two Minkowski diagrams in the drawing first...
  25. R

    Spacetime diagrams: ct axis and time contraction and length dilation

    Hi, this isn't really a homework problem... but I'm just wondering I see the time axis as c*t, now people say that its to scale the time axis so that the world line of light is 45 degrees. But if you were to multiply time by the speed of light, wouldn't you just get the units metres or...
  26. Y

    Interpreting Diagrams: Why is C_v Used in Isobaric Process?

    Hello All, I am interpreting a diagram from the following question. (I didnt have a chance to take thermo and I learned it by myself so I might have some problems) http://www.physicsgrad.com/pgre/9677-15 I understand that I can just do ΔW and I get the right answer, but upon doing it...
  27. P

    Understanding Trig In Force Diagrams

    Hello, I have the following problem part (b) which I already solved as you can see in the attached image. So I am not asking homework questions, I merely reviewing my homework for a better understanding for the test. I obtained the answer from a friend showing me his method. However, I am...
  28. B

    Help drawing free body diagrams

    Homework Statement The picture attached is the problem. Also given is the constant acceleration of 2m/s^2, a frictional force of 75N, and the mass of block A is 25kg. Homework Equations The Attempt at a Solution I just need help with drawing the free diagram part involving the normal force...
  29. L

    Tension, FB diagrams and some formula questions.

    Ok this will be a long post, sorry in advance. I am an online student of a university and the help I am getting from them is ridiculous, I am also using a book called quicksmart introductory physics, and for the most part it is quite rubbish. 1st Problem: (not homework questions, I am trying...
  30. T

    What is the significance of F being a roller joint in this system?

    Homework Statement Assume the system is massless. The Attempt at a Solution Here is my quick attempt at drawing a free body diagram for this system: What I am not sure about is the direction of the force at F. Should the force be A or B?
  31. N

    Shear Force Diagrams and Bending Moment Diagrams

    Homework Statement http://img189.imageshack.us/img189/9131/22465062cfdd4934b51d7f5.png Hopefully the image isn't too difficult to decipher... Basically a beam balanced on to pin jointed pivots with 6 metres in between each one. Homework Equations ƩFy = 0 ƩFx = 0 ƩMP = 0 The...
  32. P

    Semester Project concerning Feynman Diagrams

    Hi there everyone. I'll try to keep this short. I'm currently a sophomore at a local college. I'm in Honors Calculus 1 and part of the honors course requires a research project at the end of the semester. I'm studying to be an ER Doctor/Particle Physicist, yes I know this will take some...
  33. T

    Stuve diagrams, dry and wet adiabats

    I understand the idea that an unsaturated parcel of air will rise along the dry adiabat until the condensation level is reached, at which point the air is saturated with moisture. If it rises further, it will do so along the moist adiabat - but doesn't that mean at the same time that water...
  34. B

    How Do I Draw a Feynman Diagram for e+e- → VeVe?

    Feynman Diagrams! Please Help! Hi guys! I've been asked to draw a scattering and annihilation Feynman diagram for the following scenario: e+e- → VeVe (The second Ve is an anti-neutrino just couldn't figure how to put the bar on! :P I've tried it and I'm convinced the mediating...
  35. N

    Drawing Vector Diagrams from Point Data

    Do anyone have any software by which i can make a vector diagram from a group of points.you can think it like..suppose you have x & y component of a vector at a point..you can draw that easily but i will have to draw a vector diagram for 100 or more points arranged on a surface...i will give the...
  36. N

    Sunset / sunrise diagrams in 2D

    Hi, Can anyone point me to a reference where the complete amplitude for a sunrise diagram in 2D with generally different masses is written down. That is, I want the value of the following integral $$ \int d^2k d^2l \frac{1}{(k^2-m_1^2)(l^2-m_2^2)((p-k-l)^2-m_3^2)} $$ where p is the...
  37. S

    Logistic Map and cobweb diagrams

    Hi all. I am new here and I am having difficulty figuring out what exactly is required of me in this question. If someone could be so kind as to explain. For this part of the project we will consider the evolution of a discrete dynamical system given by a logistic map. We will consider a...
  38. D

    Optical diagrams, what program?

    First, I hope this is posted in the correct section, and I'm sorry if it isn't. I am looking to create diagrams of optical setups for a technical paper. My mentor recommended using Microsoft PowerPoint, but my diagrams don't compare to those in published papers. Is there a better program...
  39. A

    Current flow direction indication in circuit diagrams

    Hi all, I'm having a small question about current flow direction indication in circuit diagrams. Its shown as current flow from +ve pole to -ve pole, but -ve pole has higher electron concentration (potential) & electrons flow from -ve to +ve. Whats the logic of showing the direction of...
  40. E

    Question related to SHM and free body diagrams

    Homework Statement Draw three free-body diagrams showing the forces acting on a toy suspended by a vertical spring. The diagrams should show the situations when the toy is at its equilibrium position, and above and below the equilibrium position. Homework Equations The Attempt at a...
  41. T

    Number of weighted vacuum Feynman diagrams

    I didn't know where to put this, because it isn't a homework or coursework I have to do but just a thing I'm trying to understand. Anyway, I have attached the problem as an image. We have a scalar quartic lagrangian in d dimensions. It says that the number of vacuum Feynman diagrams, at a...
  42. A

    Modal Analysis - Interpretation of Stability Diagrams

    Hello! I'm doing a modal analysis and I'm trying to extract modal parameters from my aqcuired data. I'm using the Pulse Reflex Software. I got to the point where the Software provides me with a MIF and a stability diagram and I am to choose the parameters. However, I am unsure how...
  43. I

    Where can I find examples of energy band diagrams for semiconductor devices?

    Hi, I'm studying for a course in semiconductor devices, involving pn-diodes, schottky-diodes and mosfet transistors. Just wondering if there's any good online resource that demonstrates specifically how to draw energy band diagrams for the various devices in various situations (applied...
  44. S

    Software to draw free body diagrams and vector diagrams

    Hello Could anyone recommend me a software to draw draw free body diagrams, vector diagrams, spherical/cylindrical coordinates systems etc. I am doing a project on electromagnetics and I am supposed to put everything in a digital format. Thanks
  45. F

    Supression factor for triangle diagrams

    I'm pretty shaky with my understanding of much beyond simple tree-level calculations. When people talk about triangle diagrams, they sometimes say one will get a 'supression factor' of xxx. For example, in the consider the triangle diagram for H\rightarrow\gamma\gamma with Ws running around...
  46. J

    How Do You Draw Cell Diagrams Correctly?

    Homework Statement Homework Equations The Attempt at a Solution I always thought you put the electrolyte of one half cell on one side and the other electrolyte on the other side The answer given is C. But this includes VO2+ which is not in the initial eqn on the RHS?
  47. S

    Forces acting on an object -free body diagrams

    Hi guys, I have a dyanamics question to ask. Thanks for the help! In the scenario there is two objects-one the box and the hand pushing it When i push an object, there will be a force acting on the object and hence a reaction force acting on my hand. So, if i were to apply 10N of force on...
  48. P

    Velocity phase space and energy diagrams

    Homework Statement Ok I have attached the pdf file and I have a problem with velocity phase spaces (Question 3a). Honestly, the lecture notes were not very helpful and looking online and in textbooks, they talked about solving Lagrange's equations but nothing to deal with the problem of Q3...
  49. S

    Matlab Programming for Shear Force & Bending Moment Diagrams of a Beam

    Need help!Matlab programming for shear force and bending moment diagrams of a beam Homework Statement A program is required that will calculate the shear force and bending moment diagrams for a cantilevered beam of arbitrary length. The loads may be point loads or distributed loads,or a...
  50. O

    A question about electrical ground (with diagrams)

    Ok, so I've been wrestling with the concept of ground for the past two weeks. I'm in an electrical engineering program at college, and let me preface this by saying I have no difficulty dealing with ground in a practical sense and understand its general function very well. That being said, I've...
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