Recent content by abode_x

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    Commutation Relations and Unitary Operators

    I have a problem with deriving another result. Sorry I am new to this field. Please see the attached PDF - everything is there.
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    Unitary Operators and Lorentz Transformations

    Starting from: U(\Lambda)^{-1}U(\Lambda')U(\Lambda)=U(\Lambda^{-1}\Lambda'\Lambda) It says to plug in \Lambda '=1+\delta\omega, to first order in \delta\omega Working out the left hand side from the given, I end up with I+\frac{i}{2...
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    Unitary Operators and Lorentz Transformations

    Homework Statement I am trying to learn from Srednicki's QFT book. I am in chapter 2 stuck in problem 2 and 3. This is mainly because I don't know what the unitary operator does - what the details are. Starting from: U(\Lambda)^{-1}U(\Lambda')U(\Lambda)=U(\Lambda^{-1}\Lambda'\Lambda) How does...
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    Help with Simple High School Physics

    p=mv.. so if its not moving then momentum is zero. there has to be some context like maybe the final momentum when a mass is dropped from a height? or something...
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    Does f(z) have a singularity at infinity and how can its residue be obtained?

    okay so i transform z -> 1/w then take lim w-> 0... if it blows up then i do have a singularity... how do i get lim w->0 of exp(i/w) ? well first, i think i need l'hopitals (for the whole function). then, can i use the fact that when taking a limit it can be approached along any line on the...
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    Help with Parabola Question by Monday

    "Is it that the line FP is always the same length as PN? Or is that not true?" i think that's it. (look at definition of a parabola)
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    Help with Parabola Question by Monday

    considering the gradients of the lines means their slopes. that is, using the slopes show that FN is at right angles with PA. then you can use a property of a parobala that will let you conclude that triangle PAF is the same as triangle PAN. and so are the corresponding angles. then you must...
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    Does f(z) have a singularity at infinity and how can its residue be obtained?

    does f(z)=\frac{ze^{iz}}{z^2+a^2} have a singularity at infinity? if so, how do i get the residue there?
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    What is the probability of scoring a sum of 7 after 20 tosses with 2 dice?

    think of this one: 20 tosses of a single coin. what is the chance, you get a head? the easiest approach is to count the chance no head appears (all tails for 20 tosses) and subtract it to 1.
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    Calculating Electric Field of a Polarized Sphere

    Gauss's law actually gives the right answers. \sigma_b=kR everywhere on the surface if you apply the definition. likewise, \rho_b=-3k. these are symmetric and so is E inside and out. as for the r-r' hint. i don't see it yet, but i will try it. thanks. i was wrong though, about my claim that i...
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    Calculating Electric Field of a Polarized Sphere

    From Griffiths, Problem 4.1 A sphere of radius R carries a polarization \textbf{P}=k\textbf{r} where k is constant and r is the vector from the center. a. Calculate \sigma_b and \rho_b. b. Find the field inside and outside the sphere. part a is handled simply by...
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