Rules Definition and 516 Threads

Homework Statement A voltage of 60cos(4 \pi t) V appears across the terminals of a 3mF (milli-farad) capacitor. (which is equal to .003 F [farad]). Calculate the current through the capacitor and the energy stored in it from t=0 to t=.125 s Homework Equations Current through an ideal...

Like for this question. y = sqrt ( 5x - sqrt ( x^2 + 3 ) ) - this question is a square root within another square root. So I rearranged it like this: y = ( 5x - ( x^2 + 3 )^1/2 ) ^1/2 dy/dx = 1/2 ( 5x - ( x^2 + 3 )^1/2 ) ^ -1/2 x ( 5x - 1/2 ( x^2 + 3 )^ -1/2 ) I got up to there, but...

Hi, I have been looking at the renormalisation of QED and been using Peskin & Schroeder. I understand (I think) what is going on, but I am slightly confused over 2 issues: 1. In the new feynman rules from the counterterms, the feynman diagrams all have a small circle with a cross in...

RC Circuit/Kirchhoff rules question?? Regarding the loop rules. I am trying to solve a problem with 2 batteries, 3 resistors and one capacitor. I know the rules regarding the loop and traversing resistors and batteries. My question is, what happens when the direction of current I choose...

Hey friends, I am having some confusion regarding covalent character of ionic bonds (Fajan's rules) and polar character of covalent bond (electronegativity and dipole moments). We apply Fajan's rules when we start a bond to be purely ionic, as in NaCl, and derive it's partial covalent character...

Hi I'm trying to figure out how to get the electric dipole selection rules for an atom with many electrons. In all textbooks that I've seen it's shown for Hydrogen, or in the central field approximation (which is, in some sense, equivalent to Hydrogen). Obviously the central field...

Homework Statement I think I have a neat way of solving this bugger, but I'm not sure if it is a mathematically "legal" route. I don't know if there is a smarter way to solve this or not.. ∫ √(x^2 +1) dx from 0 to 1 The Attempt at a Solution I = ∫ √(x^2 +1) dx x= tanϑ √(x^2...

Please teach me this: When we use cutting rule for Bhabha scattering to cut the Feymann diagram to parts.Why we know the two parts are complex conjugation of each other,so we have optical theorem: 2ImM(s)=... M.M*... Thank you very much in advanced

Hi, So if we have an interaction Lagrangian for a Majorana field: L_1=\tfrac{1}{2} g\phi\Psi^{T}C\Psi Now looking at the path integral, I believe this must go like: Z (\eta^{T},J) ~ \exp{[\tfrac{1}{2} ig \int\,\mathrm{d}^4x (\tfrac{1}{i}\tfrac{\delta}{\delta J(x)...

I know the antiderivative of 1/(x^(1/2)) dx is 2(x^(1/2)) + constant, and i can prove it if i rewrite the inverse equation to be x^(-1/2). However, leaving it in the fraction form of "one divided by x to the one-half power", i always come up with 2/(3x^(3/2)). Am i doing something wrong...

Hi all I'm new on this forum. I'm here since I'm working with n-extended susy and R-sym and I don't know how to calculate a commutator. First of all I introsuce my notation: \mu_A T^A is a potential cupled to R-sym generator \mu_{\alpha i} is a superpotential cupled to supercharges...

The announcement and discussion thread is here. Please also read page 2 of the applicable rules. https://www.physicsforums.com/showthread.php?t=459349

Hey all, Just like to prefix this question with the statement that I am a computer scientist with a strong interest and passion for physics, so please forgive me if this question is a tad naive. With that out of the way, I have a general question about this image: It's from "The Little...

I have a problem with doing that. I've discovered some formulas for doing that, which I've found by making certain plausible assumptions and requiring self-consistency in various special cases, like adjoint -> (adjoint,scalar) + (scalar, adjoint) + (extra stuff) but I haven't found...

Hi I need help to understand Feynman rules for decay for exams. In past paper there is the following question as whether the following are allowed. cc decays to tau++tau-. From What I can see this is possible via the strong force is this correct? The next is cc decays to cu and cu. From...

I LOVE this woman! Mariska rules. When she started portraying a detective on Law and Order, SVU, who was assigned to sexual abuse cases, she got mail from victims of sexual assault/abuse. She and her husband started a foundation to help the victims of such abuse, in real-life. I LOVE this...

Homework Statement Find the potential difference between points a and b. each resistor has R=130 ohms and each battery is 1.5V Homework Equations Kirchoff's First Rule: at any junction point, the sum of all currents entering the junction must equal to the sum of all currents...

Assume I have a function: f[x,y] This function has two real values (a,b) that are very small O(0). My end result should be: F[a,b] = \int_{y_a}^{y_b} \int_{x_a}^{x_b} dx dy f[x,y] Whereupon I would then expand F about a=0 and b=0. Now my problem is that the integration is very...

trying to remember rules for curl test applicability. is it just simple closed curve? is F=-ysin(x)i+cos(x)j able to use the curl test?

Homework Statement See q attached Homework Equations The Attempt at a Solution So basically... my questions is this: I thought that the rule in quantum for p(A or B) is that A(A or B) = A(A) + A(B) then you square [A(A) + A(B)] to find p(A or B) (where A(X) is amplitude of X)...

I know this is a silly question for a 12th grader to ask but I don't know the exact rules. If we divide 950 by 121, the first digit of quotient is 7, then we place a decimal after 7 and bring one 0 down, which is correct way. In the division of 21780/704, the first digit of quotient is 3...

So, what kind of judgement could they get against a 4 year old? Can they get a judgement against future income? Put the careless kid in reform school? The article makes it sound like the judge feels the child intentionally or carelessly rammed her bike into the old woman, which may have...

I read somewhere that HNO3 and CH3COONa can act as a buffer solution. I know that the following solutions can act as a buffer- 1) A solution of weak acid and its salt with a strong base. 2) A solution of strong base and its salt with a strong acid. 3) A solution of a salt of weak acid and a...

Why is there no allowed transition from the 2s^2 S_{\frac{1}{2}} state to the 2p^2 P_{\frac{3}{2}} state in the attached image? It seems to fulfill the selection rules \Delta l = \pm 1 and \Delta j = 0, \pm 1. This is for electric dipole transitions by the way.

Homework Statement For a Lab report I have to solve for three unknown currents from Kirchoff's Rules equations using simultaneous equation algebra, and I'm completely stumped.Homework Equations From Loop and junction equations, the three equations that I have are I1 + I2 = I3 I1= (-I3R3 -...

Gents, Is there such software package or something like that... when you input the lagrangian it gives you the vertecies (Feynman rules)... Thanks

Homework Statement [PLAIN]http://img716.imageshack.us/img716/8330/werhc.png Homework Equations The Attempt at a Solution My question is what do I need to prove to show that the wave function is acceptable. So far all I can think of is showing that the wave function is 0 outside...

Homework Statement I just need to check if my answers are correct [PLAIN]http://img99.imageshack.us/img99/5139/physicsproblem.jpg a) Find # of junction points b) Find # of arms c) Find currents in all arms by applying Kirchhoff's Rules Homework Equations Current in = Current out Potential...

Hey! I am curious to know if there is any book, site, or reference material that teaches you strictly on math laws. For example, they may give you formulas (like synthetic division).. and tell you that every time you use the restriction ( that happens to be a fraction, you must divide it...

One of the rules in surds is that any number of the power of 0 must equal 1 And as Infinity is nothing more than a never-ending number then does it stand to reason that Infinity to the power of 0 must equal 1 but my question is what is 1 Is 1 (in this situation) an abstract concept or does 1...

Homework Statement Show that the set of all positive real numbers, with x+y and cx redefined to equal the usual xy and xc, is a vector space. What is the zero vector? The Attempt at a Solution My attempt stops at me trying to decipher the problem. Are they asking me to take particular...

Homework Statement The circuit in the figure is composed of two batteries (e1 = 8 V and e2 = 6 V) and four resistors (R1 = 110 W, R2 = 40 W, R3 = 30 W, and R4 = 50 W) as shown...

Homework Statement See the image http://tinypic.com/r/33z6vz5/7 Homework Equations The rules of dot product multiplication. The Attempt at a Solution I've determined that 2 of the solutions are valid, while two of the choices are invalid. I thought C and D looked correct, making A...

Homework Statement What rule of inference is used with the following statement: Kangaroos live in Australia and are marsupials. Therefore, kangaroos are marsupials. I set this up as p = kangaroos live in Australia and q = kangaroos are marsupials. Therefore, p. To me, it looks like the...

Hi again, everybody. I have been mulling over lately some important assumptions we made when thinking, but suddenly I realize I cannot justify them all. Here is one of them: Supposing there exists parallel universes, would their physics laws obey our logical rules? Or rephrasing it: Could...

I saw someone discussing divisibility rules in another thread and would thought I would make a note that the divisibility rule of 9 of summing the digits to see if you end up with 9 is really a trick of the counting base you are using (base 10). In general, this divisibility rule applies to...

I'm probably missing something small but I haven't been able to figure this out. In the Feynman rules (for a scalar field that obeys the Klein-Gordon equation), you write a propagator for internal lines as \frac{i}{k^2 - m^2 + i \epsilon}. The propagator integrand is originally...

I am new here to say all of you "hi!". Hope to be welcomed by all of you. I would like to be the part of the discussion going in this forum. And I think that you are enjoying a lot on this site. I am here for too which will enjoy soon. I am new here and I hope you will guide me to follow the...

Homework Statement give a general rule for when Integral (1/x^n) from (x, 0, a), a>0 converges or diverges. Homework Equations The Attempt at a Solution I have checked the textbooks for this answer but i can't seem to find it. The closest i got was Integral (1/x^n) from (x, 1...

I have been studying how to apply the Feynman rules for QED to various simple first order process (as prescribed by Griffiths' 'Introduction to Elementary Particles'). So far, all is well. I can follow the rules, and develop the results, and it all looks very clever. My problem is that so...

hey, I was asking myself a few questions about the selection rules for EM dipole radiation which occurs if electrons "jump" into lower bound states according to the selection rules. now I know that the full explanation about matrix elements of the dipole operator comes from fermi's golden...

Hi What rule or theorem of limits says that you can do this with a limit lim(h->0) (a+b)/h = lim(h->0) a/h + lim(h->0) b/h The book i am reading has just done something like that to a limit without saying why you can do that thanks

I have searched topics like reflection forum and I always seem to get different answers. I'm hoping to reconcile all of this, I've read FAQs, threads, wikipedia... To explain reflection I've heard these 3 explanations: 1) Light is absorbed by an atom, then re-emitted at a later time randomly...

Homework Statement Find limit lim x->0+ of lnx+1/x Homework Equations 1/x = ln e^1/x The Attempt at a Solution ln x + ln e^1/x = ln x*e^(1/x) lim x-> 0+ ln x + ln e^1/x = ln 0*inf = ln 0 = - inf lim x-> 0+ Source: my self vs http://www.numberempire.com/limitcalculator.php

Can anyone brief of on the different rules for doing ray tracing for both concave and convex lenses, as well as both concave and convex mirrors?? I understand the concepts but i can't seem to keep ray tracing in my head from the way our textbook explains it...

I know I should know this, but I have a quick question. Let's say we have a diagram: 1-->----------2 | | <- "q" v | 3--<----------4 Lets assume: 1 = "quark" 3 = "antiquark" 2 = W boson 4 = photon q = same quark flavor as "3" Time...

I am having trouble showing: <4 3 0 | p_z^2 | 4 0 0 > = 0 and <4 2 1 | x p_y | 3 1 0 > = 0 I know the usual selection rules for parity, spherical tensors (Wigner-Eckart for x,y,z) but I can't convert these two to anything I know. You could also help by telling me how to convert these to...

I always get slightly confused with the rules of differentials. now \frac{d^{2}y}{dx^{2}} is the scond derivative of the function y(x but rooting this does NOT give the first derivative dy/dx However, with the operator \frac{d^{2}}{dx^{2}}, it seems that you can root this and it DOES...

http://img17.imageshack.us/img17/201/73448266.jpg let's suppose that we know all resistors and voltages by applying kirchhof rules we have V1 - i*R1 - i*R2 -i2*R3 = 0 V1 - i*R1 - i*R2 - i1*R4 - V2 = 0 -V2 + i2*R3 - i1*R4 = 0 we know V1,V2,V3 R1,R2,R3 and we can find the currents...

Hello all. I feel like such a retard, but there's an example problem in my book with the answer, and I just don't know how they are getting the answer. I suppose it's due to my lack of mathematical skills. I was wondering if someone could guide me on how they got the answer...