Rules Definition and 539 Threads

I have found an error in the QFT book by Mandl & Shaw, 2nd ed. In eqn (8.53), there is a minus sign in front of e^4. However, this cannot be justified on the basis of how the equation is derived. In the unnumbered eqn below eqn (8.52) there is a minus sign, and the trace in this eqn is to be...

I have a couple of questions about selection rules for the hydrogen atom. When we talk about these rules in an undergraduate context we are usually assuming LS coupling where we ignore spin orbit coupling so orbital and spin angular momentum are essentially independent. Is that correct...

Hi, I am a grade 12 student, finishing my advanced functions at the moment, in a few short weeks i shall be taking calculus, in my last trig unit my teacher remarked that although i did well, i should brush up on my 'basic rules for algebra' from what i understand this is stuff that i don't...

Homework Statement Find V out by determining three equations with three unknowns. Use Mathematica to solve the system to find V out. See image for details Homework Equations -- The Attempt at a Solution Here is my code: \text{eq1}=v-i_3*(2r)-i_3*r-i_3*(2r)...

Hi Everyone I have been working on FEA for past 2 years. However my work has always been academic ( either assignments or validating certain experiments). I have never been exposed to any industry work in FEA. I am curious on how FEA is used in the industry ( specially in engineering...

Find all 10-digit numbers ##a_1a_2a_3a_4a_5a_6a_7a_8a_9a_{10}## (for example, if ##a_1= 0##, ##a_2## = 1, ##a_3 = 2## and so on, we get the number 0123456789), such that all the following hold: - The numbers ##a_1,~a_2,~a_3,~a_4,~a_5,~a_6,~a_7,~a_8,~a_9,~a_{10}## are all distinct - 1 divides...

Homework Statement Ok so I'm having trouble simplifying a part of a boolean equation. It needs to be in the form Yt(...) Homework Equations note X' means Not X The part to be simplified is.. Y(NX'Z+NX'+NZ') The Attempt at a Solution Using the rules of simplification, particularly...

Hi, So I'm doing boltzmann's entropy hypothesis. I have a basic question about the mathematics of logarithms. For \frac{ΔS}{K_B}=ln(W_f)-ln(W_i), I do the correct maths and go \frac{ΔS}{K_B}=ln(\frac{W_f}{W_i}), and finally take the log of the equation to get...

Homework Statement Use the rules of inference to prove the following: (¬p ^ q) ^ (r → p) ^ (¬r → s) ^ (s → t) ) ⇔ t. Homework Equations Rules of Inference I guess. The Attempt at a Solution Honestly I don't know where to start using the rules of inference. I drew a truth table and...

In reading Ryder's book on quantum field theory he advocates reading off the Feynman rules directly from the Lagrangian in the path integral quantization method. I can sort of do this in phi-four theory, but it is not obvious in for example Yang-Mills theory, so I wondered if someone could...

Ok what I'm trying to do is create a table where football tactics counter each other in a numbered order. Such as like a filled in order of the below table... This can be simplified into a 7x7 matrix table such as the below (by renaming the tactics, 1-7) We have 3 rules that need to be...

Would some kind soul please look over the following and check that use of the log rules, thought roundabout, is nonetheless correct? (thx kindly: I'm revising stuff I tried to cram last year) The set question: Solve for x: $$y=ln(x)+1$$ Answer given in text: $$y-1=ln(x)$$ $$\therefore \text...

Does anyone have a link or a reference to somewhere where these rules are explicitly derived for phi-four theory?

Please see attachment. What are the arrow heads supposed to mean? Only emission is allowed and no absorption? I mean, selection rules allow Δl=±1. But the figure is saying otherwise. I also read in another book, that the only series observed in absorption is that to the ground state, where...

Hi, I'm a little confused by the selection rules for atomic transitions. In pretty much any standard QM text, they derive the fact that an electron can't transition in an atom unless \Delta\ell=\pm1, i.e. unless the orbital angular momentum changes by one unit. Then the books go on to say that...

I have the following equation that I'm trying to simplify: $$\frac{5 + \sqrt{5}}{2\sqrt{5}}*(\frac{1 + \sqrt{5}}{2})^{x} $$ From looking at it, it seems like it could be simplified so that the right-hand side of the multiplication would be: $$(\frac{1 + \sqrt{5}}{2})^{x+1} $$ I started to...

Hello, I am having difficulty when trying to solve problems requiring kirchhoffs rules. The problem I seem to be having is following the convention used by my book. I can't tell when the current is gaining potential going across a resistor, or atleast going from low potential to high potential...

This forum is ONLY for the discussion of existing science fiction and fantasy stories in movies, books, tv, comics. It is NOT for discussing personal ideas, those would go in the Science fiction WRITING forum if they adhere to the rules for that forum. This forum is not for new ideas or...

Homework Statement y=\frac{}{}tsint/1+t Homework Equations The Attempt at a Solution What I do (and arrive at the wrong solution) is the fallowing. Can you please tell me where i go wrong. *I am going to leave out the denominator as i go through the problem because it stays the...

Hi everyone. I have a very silly question. What is the Feynman rule for external legs of spin-zero boson? Is it just to multply by 1? Thank you

Having an issue with applying logarithm rules. I'm trying to find the value of an exponent in an equation of the form: A=B\frac{(1+x)^n-1}{x} I have reviewed logarithm rules and cannot get to the answer, n, which is the only unkown variable in the equation. I've divided A by B, but am stuck at...

Hi guys! A serious doubt just passed through my mind. It is probably a silly question. In writing the Feynman rules for QCD, we know that the quark-gluon vertex is given by: $$-ig\gamma_\mu T^a_{ij}$$ where T is the SU(3) generator and i and j are the colors of the incoming and outgoing...

I'm trying to find the integration of my function f[x] from 1 to 4 using the indefinite integral and inserting limits using rules. I am not sure how to insert the limits with rules, have been playing about with the following Integrate[f[x], x] /. x -> {1 >= x <= 4} which ain't working, any...

If you have a meson in the states ## ^3S_1## and ## ^1S_0 ## this means that ##J^P = 1^+ ## and ## 0^+## doesn't it? But if you have excited states ## ^1P_1 ## this is ##J^P=1^- ## but isn't ## ^3P_1 ## supposed to be ##J^P = 1^- ##? Does this matter? ##^3P_0##, ##^3P_1## and ##^3P_2## for...

Homework Statement Find the unknown current I1 and I2 in the circuit shown below. (Reference problem 7 on the PDF doc) Homework Equations V=iR i1=i(R4/(R12+R4)) i2=i(R12/(R12+R4)) The Attempt at a Solution I used V=ir where V=20v and R=2ohm so i=10A. Then plugging into i1...

What are the rules of analytical – not numerical (matrix) entry of bra-ket convertion – operations on bra-ket, in particular – tensor product ? For example – how in analytical form to do this: U|\Psi\rangle where: U=I\otimesI I=|0\rangle\langle0|+|1\rangle\langle1|...

I'm looking for a list of inference rules used in physics derivations. I think this would be distinct from Wikipedia's list of inference rules. As an example of what I'm referring to, suppose two steps in a derivation are T=1/f Multiply both sides by a value, where the value here is f. T f...

Hi all, Having learned much about technicalities in Grand Unified Theory, I have known that it's basically pursuing the belief that coupling constants of all interactions converge to the same value. My question is, do Feynman rules still hold in this theory (b/c each type of interaction...

Hello, I am trying to compute feynman diagrams with the feynman rules but I encounter some difficulties... Since the gamma matrices, spinnors, etc do not comute, the ordering of the different factor from feynman diagram has an importance. Is there some rules that say where to begin and in...

Homework Statement Use Kirchhoff’s junction rule and loop rule (twice) to find the effective resistance of the two resistors connected in parallel as shown, and demonstrate that this agrees with the expression 1/R = 1/R1 + 1/R2 (poorly drawn picture of the circuit) The Attempt at a...

My loop 1 equation is I1R1 + I2R2 + E1 = 0 simplified to: 4I1 + 2I2 + 28 = 0 Loop 2: I3R3 - E2 - I2R2 = 0 simplified to: 1I3 - 7V - 2I2 = 0 And my node 1 equation is: 0 = I1 + I2 + I3 So doing algebra.. I get my I1 to equal 7.. which doesn't match with the -5A for I1 as given in the...

Homework Statement What must the emf ε in the figure be in order for the current through the 7.00 ohm resistor to be 1.75A? Each emf source has negligible internal resistance. Homework Equations Kirchhoff's Rule: \sum I=0 junction rule \sum V=0 loop rule The Attempt at a Solution...

Homework Statement Homework Equations Kirchhoff's loop rule and (maybe) Kirchhoff's current law The Attempt at a Solution So I attempted to apply Kirchhoff's loop rule to the circuit, and ended up with a system of linear equations: 24 - 6I_{1} - 3I_{3} = 0 \rightarrow...

Company "rules" Is your company allowing you to play online games at free time ? I like to work for companies that allow me to do what I want (provided that I don't ruin company's reputation or annoy other people) and they must pay me OT if they ask me to work OT for a project...

Homework Statement The circuit shown in the figure below is connected for 3.10 min. (Assume R1 = 7.90 Ω, R2 = 2.60 Ω, and V = 16.0 V.) The circuit shown in the figure below is connected for 3.10 min. (Assume R1 = 7.90 Ω, R2 = 2.60 Ω, and V = 16.0 V.) Homework Equations Kirchoff's...

Homework Statement Apply the loop rule to two of the three loops to calculate I1,I2,and I3. Picture of DC circuit involved Homework Equations V=IR The Attempt at a Solution L1=2v+2I2-4I1=0 (simplified) and L3=4-4I1-5I3=0 But if you work through the algebra you'd get I2=1...

Homework Statement I have the equation (sin(2x))/x = ? The Attempt at a Solution I know that the answer to this is 2, but I am not sure why (sin(2x))/x = 2 Can somone explain? Thanks

Homework Statement A metal strip moving to the right in a B field which is going into the plane of the page. Can this problem be considered using both Fleming's right and left hand rules? Homework Equations The Attempt at a Solution If I consider Fleming's left hand rule: the negative...

Homework Statement What currents are provided by the batteries? What is the voltage drop across the 1.2 Ω resistor? Homework Equations V = IR Junction Rule = sum of current at a junction = 0 Loop Rule = sum of changes in potential around any closed path of a circuit must be 0 The...

Show G(k)=\sqrt{2π}g1(k)g2(k) Given that G(k) is the Fourier transform of F(x), g1(k) is Fourier trans of f1(x), g2(k) is Fourier trans of f2(X) and F(x)=^{+∞}_{-∞}∫dyf1(y)f2(x-y) SO FAR G(k)=1/\sqrt{2π}^{+∞}_{-∞}∫F(x)e-ikxdx <-def'n of Fourier transform...

The other day our lecturer was going through field axioms, rules of numbers, I guess what you'd call very elementary number theory. In particular, he was explaining what you can and can't do with ∞, and he mentioned that x/∞=0. I guess I'd just like some clarification on this. Should this not...

Homework Statement Use Kirchoff's rules to determine I1, I2 and I3 for the following circuit: Use the following values:ε = emf = 9 V r = internal resistance = 1.5 R1 = 5 R2 = 15 R3 = 13.75 Homework Equations The Attempt at a Solution I found I1 to be .9328 by adding all the...

Hiya folks, In an effort to get the students in my Advanced Physics class to rely less on calculators and to develop their math skills, I am going to give them the option of using slide rules this year. I am offering them a small bonus on tests if they use slide rules instead of calculators...

In this forum, it is possible for writers to ask for help with science-fiction or fantasy stories. Since science-fiction is speculative in nature, some degree of speculation is allowed here. However: There can be no speculation about the real world and about known science. Rather, all...

I'm studing the basics of renormalization (with phi^4 theory) and once you write the renormalized lagrangian with the counterterms, how do you derive the feynmann rules asociated to the kinetic counterterm? ---∅--- = i(p^2 δ Z - δ m) How??...

Walking the dog takes me past an odd (to me) looking pine tree. I live in south eastern Pennsylvania. With help of Google I think the tree in question is a White Pine, see http://www.oplin.org/tree/fact%20pages/pine_white/pine_white.html Also see the images below of the tree. I don't think...

From the image attached: A. Calculate the current through the 22Ω resistor. B. What is the voltage across ab Here is what I've done: A. ) I labelled the currents and applied the Junction Rule I1 + I2 = I3 -I1*22Ω + 8V + 13*6Ω + 18V - I3*6Ω = 0 -I1*22Ω + 8V + I2*14Ω - 12V = 0...

I posted this in the number theory forum to no success... so I figured maybe the homework help people would have some input Let x,y,z be integers with no common divisor satisfying a specific condition, which boils down to 5|(x+y-z) and 2*5^{4}k=(x+y)(z-y)(z-x)((x+y)^2+(z-y)^2+(z-x)^2) or...

I have grammar S → ABaC | BaC | AaC | ABa | aC | Aa | Ba | a A → B | C | BC B → b C → D D → d Can someone please help me to eliminate all the rules of grammar production unit. Thanks for help! :biggrin:

I am having trouble finding the rule for the (partial) derivative of an expression like y = f(X)^{g(X)} can anyone help?