Rules Definition and 516 Threads

Hello! I just want to clarify something about the rules on solving quadratic eqns. I have already solved both problems but in the process of my solution some questions arise. For example in the part of my soltution in problem 48 I have this...

I came across this article, called "Ten Simple Rules for Effective Statistical Practice", and thought it was monumental in its importance for understanding statistics and using it practically, particularly in science. I hope you enjoy it!

Homework Statement Hi everyone, I'm currently working on year 12 maths and am able to answer questions in the maths book for the various rules of differentiation (chain, product, quotient) and can determine which questions should be answered using which rules. But in the maths book, the...

Homework Statement i was told by my lecturer that when we choose the repeating variables in pi buckingham theorem , we can choose based on 3 property , which is geometry property which consists of (length , width and area) , then followed by flow property ( velocity , acceleartion, discharge)...

Homework Statement A moving particle encounters an external electric field that decreases its kinetic energy from 9480 eV to 8260 eV as the particle moves from position A to position B. The electric potential atA is -43.0 V, and that at B is +25.0 V. Determine the charge of the particle...

Homework Statement Homework Equations i1+i2-i3=0 50i1+75i3=1 100i2-75i3=1 The Attempt at a Solution matrix A=1 1 -1 0 100 -75[/B] 50 0 75 matrix B= 0 1 1 i1= -6ma i2= 23ma i3= 17ma My instructor gets i1= 6ma...

Hi, I am studying the dynamics of a trapped ion in a laser and am trying to simulate the dynamics via a quantum jump, in order to do this I need to know the allowed transitions that the ion external and internal degrees of freedom can take, being the number state (n) of the approximated harmonic...

Homework Statement I am trying to calculate the selection rules from 2p to 1s. Above are the three results in (1152)-.(1154). And In the image one also finds the spherical harmonics factors. I can not determine which R and angular parts that give the three 2p waves. Can you show which ones...

Homework Statement We are given that R1 = 15.0 Ω, R2 = 10.0 Ω, and R3 = 8.00 Ω. What is the current and direction of the current through each resistor? Again, I have no idea how to do this, I got my answer from chegg, but I don't know if this is correct. Homework Equations V = IR[/B]The...

On the bottom half of page 249 Cohen-Tannoudji it talks about selection rules in terms of off diagonal elements of the matrix generated by ##\langle \phi _{ n^{ \prime },\tau ^{ \prime } } \mid \hat { B } \mid \phi _{ n,\tau } \rangle##. I thought all off diagonal matrix elements would be...

I have a left-handed ##SU(2)## lepton doublet: ## \ell_L = \begin{pmatrix} \psi_{\nu,L} \\ \psi_{e,L} \end{pmatrix}. ## I want to know its transformation properties under conjugation and similar 'basic' transformations: ##\ell^{\dagger}_L, \bar{\ell}_L, \ell^c_L, \bar{\ell}^c_L## and the general...

I have the solution for this problem but don't understand it. 1. Homework Statement Use Hund's rules to calculate the ground state of erbium with electron configuration [Xe]4f126s2 Homework Equations Hunds Rules: 1. Maximise S (within Pauli) 2. Maximise L (within Pauli) 3. Min J (for...

Dear All. My hobby is road traffic and road rules. For me is very interest rules in other countries. I want read official text of rules in your country. Please add link for official text if you know. In English please if you can. My English is not good. I search in Google but not got correct...

Are their specific laws or rules in emergence? For example, temperature is emergence from the underlying particles. Superconductivity is emergence from the cooper pairs. It seems you can turn off emergence by say increasing the temperature to disable the cooper pairs. In temperature, how do you...

While I am reviewing my undergrad physics for qualifying exam, I became confused about the numerous selection rules. (1) We have the selection rules for spontaneous emission in a hydrogen atom: Δl=±1 ,Δml=0,±1. This rule is the easiest to understand by evaluating <n'l'm'|z|nlm> (2) We have the...

Are there any rule guides on fixed format Fortran such as in .f77, .f, .for files? For example, http://www.physics.nau.edu/~bowman/PHY520/F77tutor/03_basics.html has a few snippets of rules for Fortran 77 such as Col. 1 : Blank, or a "c" or "*" for comments Col. 1-5 : Statement label...

Given a diagram, how is one supposed to apply the feynman rules to calculate the feynman amplitude?

We can easily find out below rules in set theory: 1. Let consider set “A” as follows: A = {a1, a2, a3, a4… an} and also power set of A is set C: C = {{}, {a1}, {a2}, {a3}, {a4}, {a1, a2}, {a1, a3},….{an}} Rule 1: To find the number of subsets with precise members number, we can use Binomial...

Homework Statement Homework Equations With what equations i can express the fact that when dc is aplied to transformer there is mutual inductance only when the voltage is turned on or off and there is no positive feed back represented as an infinite inducyion between the 2 coils? The Attempt at...

Homework Statement The lagrangian is given by: L = \frac{1}{2} \partial_{\mu} \phi \partial^{\mu} \phi + \frac{\alpha}{2} \phi \partial_{\mu} \phi \partial^{\mu} \phi And the question is to find the feynman rules. Homework EquationsThe Attempt at a Solution I started by using the...

Hello, i just discovered this site and i love the work you guys are doing, helping people like me with math and physics etc. I was wondering if anyone knows a website / list / etc with math-rules, like algebra, logarithms, power, rules for differentiation, elasticity, substitution, sequence...

Hallo Everybody, I am searching for a book (or lecture notes) that details the calculations that lead me from a given Lagrangian to the Feynman rules of the theory. It should not be rigouros, just the main steps to get the Feynman rules. Thanks for your help!

Good afternoon, Does the selection rules have a condition on \Delta n ? I have not found a website or a book that show transitions between 2S_{1/2} and 2P_{3/2}, that's why I was wondering if \Delta n = 0, with respect to the other selection rules, are allowed transitions. Thank you for your...

Its usually said(like https://en.wikipedia.org/wiki/Superselectiond ) that superselection rules imply that not all Hermitian operators can be considered to be physical observables. But I don't understand how that follows. Can someone explain? Thanks

Specifically when doing integration problems. I know the indef integral of cosx/sinx+1 is ln(sinx+1) + C, but absvalue is not required here. I think it's because the sine fn must be >= 0 or it's undefined? What about in other cases, is there a general rule to know when to use absvalue? Thanks

To be specific, I am referring to CO molecules undergoing collisions with H2, resulting in CO transitioning to an excited vibrational state. I can't seem to find any rotational selection rules for collisions, meaning ΔJ could be essentially anything, as long as energy and angular/linear momentum...

OKay, so whenever I run into explanations on the cutting rules, most of the time I see the statement to replace##\frac{1}{p^2 - m^2 + i\epsilon} \rightarrow -2i\pi \delta(p^2 - m^2)## for each propagator that has been cut taking note that there is no factor of i in the numerator for...

http://www.independent.co.uk/news/science/what-exactly-does-one-mean-court-of-appeal-passes-judgement-on-thorny-mathematical-issue-10350568.html Thoughts?

Dear PF Forum, I just read Math FAQ Please confirm. These rules are not int practice. Is this true? Because 30 years ago in high school, I was taught. x/zero is infinity, error in computer. zero/zero is undefined, not zero. Also error in computer. So zero/zero is undefined or zero? Thanks for...

Homework Statement Where V1 = 14V and V2 = 10V, solve for I1, I2, and I3. Homework Equations DeltaV = IR Sigma(I) at junction = 0 Sigma(DeltaV) of loop = 0 The Attempt at a Solution I began by assuming clockwise direction of the loops, to determine the signs of the resistance to follow. I...

According to rules for working with approximate data, why the final result of a multiplication or division involving approximation data is round off so that the result has as many significant digits as the given data with the fewest significant digits? How is this rule established? For example...

Hi, i have some trouble with feynman rules after wick's rotation. I don't understand how the propagators transform. In particular if i take the photon's propagator in minkowskian coordinates i don't understand where the factor "-i" goes after the transformation. ## \frac{-i\eta_{\mu\nu}}{p^2}...

I have recently discovered some mathematical rules by trial and error. Some of these may be already known to people of mathematics. 1. This one is common: Sum of all integers 1+2+3+...=0.5(n^2 + n) 2. Sum of odd integers: 1+3+5+7+9...= n^2 3. Sum of even integers: 2+4+6+8...= n^2 + n eg...

Hi, I was wondering if anyone has any advice on when to use FLHR and FRHR in the Edexcel A - Level Physics, as I'm mixing them up in questions. Thanks, Abby

Is a new article, btw June 2, 2015 Experiment Provides Further Evidence That Reality Doesn't Exist Until We Measure It http://www.iflscience.com/physics/measurement-rules-quantum-universe http://www.sciencealert.com/reality-doesn-t-exist-until-we-measure-it-quantum-experiment-confirms any...

Bohm's deterministic theory was designed to be equivalent to standard QM, but what I'm not sure about is whether that includes Von Neumann's rules. Von Neumann's rules for the evolution of the wave function are roughly described by: Between measurements, the wave function evolves according to...

Nonlinear sigma models are particular field theories in which the fields take values in some nontrivial manifold. In the simplest cases this is equivalent to saying that the fields appearing in the lagrangian are subject to a number of constraints. Since the lagrangian fields are not independent...

Hi. Do you know any book/paper/lecture notes where I can find complete derivation of Feynman rules for both scalar and pseudo-scalar Yukawa theory, and maybe an example of application to decay of fermion?

Homework Statement A circuit contains 9V battery ,which internal resistance is unknown, an ammeter and a voltmeter, whose resistances are also unknown. When a resistor was connected to the voltmeter in parallel, the voltmeter's value was reduced 2 times and the ammeter's value doubled. What did...

Some literatures say that the selection rule in electric dipole approx. for angular momentum ##\Delta j = 0,-1,1## some other say ##\Delta l = -1,1##. I follow the notation used in my references, despite the difference I think since j and l are both angular momenta which fulfill angular momentum...

Whats the circumtances which physics rules collapse and don't work.Theres any explanation it to use mathematics. Here I don't mean singularity things.I know in singularity physics rules collapse I want to talk more generally.

So the total angular momentum operator J commutes with any scalar operator S. The argument for this is that J is the generator of 'turntable rotations' (by this I mean we rotate the whole object about an axis, along with its orientation) and the expectation value of any scalar operator has to be...

I know De-Morgan's law that $$ -(p∧q) = -p∨-q $$ Also $$ -(p∨q) = -p∧-q $$ But for material implication and bi conditional operations there are also some transformation. What is the law or proof for it? Like $$ p⇒q = -p∨q $$ $$ p ↔q = (p∧q) ∨ (-p∧-q) $$ There may be other properties also that I...

http://news.sciencemag.org/sites/default/files/styles/thumb_article_l/public/article_images/sn-gammarays.jpg?itok=vYTMw8My Researchers at Institut Laue–Langevin have found a way to bend gamma rays. Gamma ray lenses, which theory had suggested were impossible, could be made from heavy elements...

Homework Statement 2. Evaluate the determinants ## \begin{vmatrix} 1 & 1 & 1\\ x & a & b \\ x^2 & a^2 & b^2 \\ \end{vmatrix} ## ## \begin{vmatrix} x & a & b \\ x^2 & a^2 & b^2 \\ x^3 & a^3 & b^3 \\ \end{vmatrix} ## and factorize both answers. Homework Equations Rules of determinants are...

Hi guys, I'm assume that you already know the 7 crystal system, each crystals have unique way of determining the family of planes, for example in cubic, we all know (111) plane is same (-1-1-1), and so on ((-1-11),(-11-1)...) a total of 8, in fact there is pattern to determine how many possible...

I have attached the properties/rules that will aid in simplifying the 3 x 3 determinant so that it can be calculated with minimum effort. I am trying to understand rule (2) and (4). I am not so clear about the idea of linearity. Can anyone please explain these two rules with regards to example...

Are there any generally accepted techniques for maximizing cell phone reception with regards to phone orientation? When I search for this question on Google I get "answers" that seem more opinion than anything. Any engineers in the house with definitive experience with this topic and confident...

When we first learn of selection rules for atomic transitions, we learn that electrons have to change between states that differ in angular momentum by at most 1ħ, because photons have 1 unit of spin angular momentum. However, photons can have arbitrarily high integer quantities of orbital...

Homework Statement Consider the following real scalar field in two dimensions: S = \int d^2 x ( \frac{1}{2} \partial_\mu \phi \partial^\mu \phi - \frac{1}{2} m^2 \phi^2 - g \phi^3) What are the Feynman rules for calculating < \Omega | T(\phi_1 ... \phi_n ) | \Omega > 2. Homework...