Rules Definition and 539 Threads

  1. PcumP_Ravenclaw

    Factorizing determinants and rules to simplify them

    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...
  2. R

    Rules in determining family of planes in Hexagonal

    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...
  3. PcumP_Ravenclaw

    Applying rules to simplify a 3 x 3 determinant

    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...
  4. DocZaius

    Maximizing Cell Phone Reception with Orientation Rules?

    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...
  5. Z

    Selection Rules and Light with Orbital Angular Momentum

    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...
  6. G

    Feynman rules for this real scalar field in 2d

    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...
  7. G

    Feynman rules - where do the imaginary numbers come from?

    I'm trying to learn how to derive Feynman rules (what else to do during xmas, lol). The book I'm using is QFT 2nd ed by Mandl&Shaw. On p 428 they're trying to show how to derive a Feynman rule for W W^\dagger Z^2 interaction term g^2 \cos^2\theta_W\left[W_\alpha W_\beta^\dagger Z^\alpha Z^\beta...
  8. T

    Nuclear Spin and Selection Rules

    Suppose we define the total angular momentum as F = I+J where I is the nuclear spin angular momentum and J is the total electronic angular momentum. mF and mJ are the respective magnetic quantum numbers. The relevant F selection rules are delta_mF = 0, 1 and -1, delta_F = 0, 1 and -1. And...
  9. R

    Transition Moments and Selection Rules

    My instructor was talking about allowed transitions for IR spectroscopy and how you can predict them relatively well using PIB wavefunctions. It was stated that you could solve for the probability of a transition moment to determine if a transition is forbidden or not. <μ>=∫ΨfμΨidτ...
  10. A

    Understanding Limits: Addition and Multiplication Rules

    (I have posted this in this section, rather than homework, because I hope to improve my general understanding of methods of finding limits through these problems.) 1: \lim_{x\rightarrow0} (\frac{cosec(x)}{x^3} - \frac{sinh(x)}{x^5}) I don't really know what to do with this one. I tried...
  11. Xenosum

    How to order Feynman Rules for Fermions

    Homework Statement This is more of a general question-- as the title suggests I'm not too sure how to place the terms given by the Feynman rules for fermions (since they involve operators and spinors, the order does of course matter). I've been reading Peskin & Schroeder and the rules are...
  12. M

    MHB Applying the rules for exponents

    Hi Guys and Grillz Im not sure how these forums work, but if someone could help me real quick by explaining me how i should count this (3x2y)^8 (2xy)^3. I am sorry if i asked a dumb question or posted it in the wrong place. This is my first time doing this. :D
  13. T

    Photon angular momentum and magnetic quantum number selection rules

    For an atom, the single photon electric dipole selection rules for the magnetic quantum number require that delta_m = -1, 0 or +1. As I understand, the physical explanation for this set of selection rules is usually related to the conservation of the projection of the angular momentum on the...
  14. S

    Band theory electron counting rules for metals/insulators

    I'm a little confused by the description I commonly hear about the electron "counting rule" in band theory. The general statement I find is that a solid with an "odd number of electrons per unit cell is a metal" (because this would imply a partially filled band), while an "even number of...
  15. R

    What is the current through each resistor in this circuit?

    Consider the circuit shown in the figure . Suppose the four resistors in this circuit have the values R1 = 12 , R2 = 6.0 , R3 = 7.3 , and R4 = 15 , and that the emf of the battery is E = 18V . (1) Find the current through each resistor using the rules for series and parallel resistors. Answer...
  16. P

    Using Bohr quantization rules to calculate energy levels

    Homework Statement Use the Bohr quantization rules to calculate the energy levels for a particle moving in a potential \begin{equation} V\left(r\right)= V_0 \left(\frac{r}{a}\right)^k \end{equation} where k is positive and very large. Sketch the form of the potential (done) and show that the...
  17. C

    Did my teacher make a mistake? (Kirchoff's Rules)

    Consider the electric circuit shown in the figure. Using Kirchhoff's rules, select True or False for the following equations. a.) I2 + I3 = I1 b.) ε1 - I2R2 - I3R3 - I1R1 = 0 c.) ε2 - I1R5 - I3R3 - I2R4 = 0 http://tinypic.com/r/2zyws55/8 My answers were: True, False, False. However, the...
  18. M

    Integration of A exp( (− 3 R^2)/(2Na^2)) (whilst following forum rules; I think)

    Homework Statement A exp( (− 3 R^2)/(2Na^2)) I wish to integrate ^ The expression is equal to P(N,R) The limits are infinity to -infinity. The intention is to find the normalisation constant / A in terms of N and a (then to cube it).The Attempt at a Solution This is what I've managed. A S...
  19. M

    Rules for Multiplying and Adding in Modulo # Calculation

    Hi, Are there any rules against multiplying or adding first when using modulo #? The reason I ask is because I'm doing the dot product for two vectors: [10, 9, 8, 7, 6, 5, 4, 3, 2, 1].[8, 0 ,3 ,7, 0, 9, 9, 0, 2, 6] By doing this, I get: 80 + 0 + 24 + 49 + 0 + 45 + 36+ 0 + 4 + 6 =...
  20. George Jones

    Rules for Female Teachers (1915)

    Source: the website of University of Toronto's The Ontario Institute for Studies in Education, http://fcis.oise.utoronto.ca/~daniel_sch/assignment1/1915rules.html
  21. 4

    [Highschool Physics] Kirchoff's Rules

    Homework Statement http://imgur.com/XXPWbCN Homework Equations ∑ ΔV (closed circuit) = 0 ∑ I (in) = ∑ I (out) The Attempt at a Solution So I know that the sum of the currents entering any junction in a circuit must equal the sum of the currents leaving that junction, and that the...
  22. B

    Kirchoff's rules and capacitors

    Hello, I thought I had questions concerning Kirchoff's rules down to a tee, but now capacitors have entered the scene and I'm stumped. Homework Statement The circuit in the drawing (attached) shows two resistors, a capacitor, and a battery. When the capacitor is fully charged, what is...
  23. H

    Don't understand rules of continuity/discontinuity with Limits

    Hi, My textbook is giving me 3 rules that must be met to be continuous: I don't understand what my textbook is trying to explain to me, - ƒ is defined at a...:confused: -Lim ƒ(x) = ƒ(a)...:confused: x→a all i undersdand is that if you draw a graph that is continuous, you must be...
  24. S

    Can Logical Inference Prove an Engineer Likes Both Video Games and Literature?

    Homework Statement Consider the following statements. All engineers either like computer or like power tools. All engineers who like computers like video games. All engineers who like power tools like camping out. Some engineers like literature. Based on these given statements, show that...
  25. B

    Solving Kirchhoff's Rules: Find Currents in a Circuit w/2 Batteries

    Hi, i'm stuck on this problem and have been trying to identify where I might have made an error but have come up empty. I have assigned my loops and junctions and have three equation for three unknowns, but can't seem to solve them... Homework Statement Consider the circuit in the...
  26. N

    Kirchhoff's Rules: Circuit Question

    Homework Statement If R1 is 3Ω, R2 is 6Ω and R3 is 9Ω, what are the three currents in figure 16-4, in which the batteries are 6.0v and 12.0v? Homework Equations I1+I2+I3 The Attempt at a Solution I've got three equations so far I worked out +6-3I1-9I2=0 and...
  27. 1

    Rules of Parity and Charge Conjugation Parity

    I have two related questions to ask relating to statements found in introductory particle physics textbooks. The first is that the "Dirac equation predicts fermions/anti-fermions have opposite intrinsic parity". I have attempted to verify this by applying the parity transformation to free...
  28. Hepth

    Mathematica Mathematica : Noncommutative Multiply and Replacement Rules

    Val[a_] := ToCharacterCode[ToString[a]][[1]]; GH[a].GH[b].GH[c].GH[d].GH[b] //. {GH[a_].GH[b_] :> If[Val[a] > Val[b], GH[b].GH[a], GH[a].GH[b]]} I have the noncommutative multiply of GH[a].GH[b].GH[c].GH[d].GH[b] My goal is to order these in increasing charcter value. (Val is the function...
  29. S

    Does BICEP2's observation rules out ekpyrotic cosmological model ?

    Dear every specialists, I heard that BICEP2's observation r=A_t/A_s=0.2 n_t=0 indicate two things: 1) n_t=0 excludes ekpyrotic cosmological model (ECM) definitely because ECM predicts n_t=2 2) r=0.2 excludes almost all current string inflation model (SIM) such as KKLMMT because this...
  30. Y

    MHB By using rules of inference how the valid conclusion can be determined?

    Honestly, I do not really understand how to apply rules of inference. So i would appreciate if u could explain without missing any point. I think i got this, is this the correct answer? Pls refer to image.
  31. N

    Matrix Inversion and the Associative Property

    Homework Statement Is it true that: (ABA^-1)^8 = AB^8A^-1 for all n x n matrix and not just for invertible matrix? My attempt: (ABA^-1)^8 =A^8B^8A^-8
  32. N

    What do the fusion rules in CFT mean when coefficients are larger than 1?

    Hi everyone, This is a question about conformal field theory. Even though it is not directly about beyond the SM, it seems like an appropriate place to ask since it is an important tool in string theory. I am confused by the fusion rules \phi_i ~ \phi_j = N^k_{ij} \phi_k (where as...
  33. O

    Using Formula on Page 13: What Are the Rules?

    When can you use this formula? On page 13 it uses it here: http://web.mit.edu/8.02t/www/802TEAL3D/visualizations/coursenotes/modules/guide06.pdf however my instructor said that you can only use it when you are using a wire and the current is flowing parallel to the axis.
  34. G

    How to differentiate 1/y without making a fundamental mistake?

    Problem statement Find dy/dx Revelant equations None Attempt at a solution This is what I got to so far but now I'm stuck... Any hints?
  35. J

    Basic DC Circuits - Kirchoff's Rules Lab questions

    Homework Statement I need to come up with a formula to solve for i2 given the diagram of the circuit attached. I can identify 2 junctions and 3 loops. Homework Equations *The algebraic sum of the currents into any junction is 0. By convention the currents entering the junction are positive...
  36. A

    Rules for transforming operators

    The attached picture shows a representation of a general operator, which I found quite weird. The matrix elements are calculated in the position basis as far as I can tell, but I am not sure how. Do they do something like? <klTlk'> = ∫ dx dx' <klx><xlTlx'><x'lk'> In that case what happens to...
  37. T

    Are there road traffic rules in Space?

    Are there "road" traffic rules in Space? Do you have to "stick to the left of your orbit" or "give way to the unmanned vessel"?
  38. L

    Qualitative explanation of radiative transitions and selection rules.

    Hi, I'm looking get a deeper conceptual grip on A&M spectroscopy, particularly what actually goes on between atoms/molecules and photons during an emission/absorption event. In general I just want to understand the "why's and how's" of the selection rules for dipole/quadrupole transitions, but...
  39. I

    Error of Simpson's, Trapezoid, etc. Rules

    I learned this a while ago in my calculus 2 class and I was just thinking about it... Where do these error equations for each of the approximation rules come from? Like for example, where does the error for the Simpson's rule, $$|E_{S}|\le \frac{M(b-a)^{5}}{180n^{4}}$$ come from? Also, why even...
  40. H

    Coordinate transformation for line integrals; quadrature rules

    Hi all, The context of this problem is as follows: I'm trying to implement a discontinuous finite element method and the formulation calls for the computation of line integrals over the edges of the mesh. Anyway, more generally, I need to evaluate \int_{e}f(x,y)ds, where e is a line segment...
  41. B

    Which rules to use (Product rule?)

    Homework Statement Find the gradient of the curve at the given point on the curve y = \frac{(√x - 1)}{√x} where x = 9 Homework Equations y(x) = u(x)v(x) dy/dx = u(dv/dx) + v(du/dx) The Attempt at a Solution my problem really boils down to rearranging the function to a form...
  42. G

    Quantum Zeno effect rules out many-worlds?

    Hi, I've read somewhere that the Quantum Zeno effect, should it really exist, rules out the many-worlds interpretation. However I did not understand the argument (actually there was no argument, seems the author considered it obvious). Could someone please elaborate on this? BTW, what's...
  43. Evo

    What are the guidelines for discussing speculative topics in the forum?

    In addition to the Global Guidelines, these rules also apply to posts in the lounge. Overly Speculative Posts It is against our Posting Guidelines to discuss new or non-mainstream theories or ideas that have not been published in professional peer-reviewed journals or are not part of current...
  44. MarkFL

    MHB Justine's question at Yahoo Answers regarding the Midpoint and Trapezoidal Rules

    Here is the question: I have posted a link there to this topic so the OP can see my work.
  45. M

    Kirchhoff's Rules Homework Solution

    Homework Statement Find Kirchoff's laws for this http://postimg.org/image/d78dvdg5f/ (Actual problem has a bit more but I can do that part.)Homework Equations Loop rule Junction ruleThe Attempt at a Solution I got the following equations 2e - 4i_4 - 2i_2 = 0 e - 3i_3 - i_1 = 0 e - 4i_4 -...
  46. M

    Superselection Rules: Pi+ Decay Processes Explained

    I was just reading that because of superselection rules we cannot superpose two particles with different electric charges. But when I look in my particles physics books it seems there are decay processes that do this all the time: consider \pi^+ → μ^+ +\nu_\mu , for example. Can anyone tell me...
  47. P

    Kirchhoff's Rules. Solving for currents in circuit with two batteries

    Homework Statement What are the sizes and directions of the currents through resistors (a) R2 and (b) R3 in Fig. 27-42, where each of the three resistances is 4.0 Ω? Homework Equations ΔV=IR The Attempt at a Solution Equations: 1) ΔVB2 -(i1)R1 -(i2)R2 -ΔVB1=0 5V - 4(i1)...
  48. S

    MHB Derivatives of $\frac{a}{1-r}$: Exploring the Rules

    I am having a little trouble remembering the rules with derivatives. $\frac{a}{1-r}$ I know that it should be (derivative of the top*bottom - top*derivative bottom) / (bottom squared). $\frac{d}{dr}\frac{a}{1-r}$ I tried this got the answer wrong, and looked up how to do this and they showed...
  49. Z

    Power rules for radical roots and rational exponents.

    Hello everyone, I am a bit confused about definitions rules. I can have more questions but for now I want to ask only one question: Let us say I have a number: \sqrt[6]{3x3x3x3x3x3} 3x3x3x3x3x3 is equal to both 27^2 and (-27)^2. But If I write these two expressions separately I can get...
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