Recent content by Bapelsin

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    Feynman parameter integral

    I'm trying to show equation (6.39) on page 189 in Peskin & Schroeder. Homework Statement Show that \frac{1}{AB}=\int_0^1dxdy\delta(x+y-1)\frac{1}{(xA+yB)^2}. Homework Equations Defining property of Dirac delta function: \int_{-\infty}^{\infty}dx f(x)\delta(x-x_0)=f(x_0) Also...
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    Where does the factor (2π)³ come from in QM Fourier transform convention?

    Homework Statement I'm trying to follow the solution to a homework problem in QM, and I don't fully understand this step. Where does the factor (2\pi)^3 come from? \int...
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    Electrostatics: work moving point dipole

    Homework Statement Two electrical dipoles with dipole moments \vec{p}_0=p_0\hat{y} and \vec{p}_1=p_1\hat{y} are located in the xy-plane. \vec{p}_0 i located at the origin and \vec{p}_1 is initially in (x,y)=(a,0). What work is required to move \vec{p}_1 (with unhanged directon) to the point...
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    Electrostatics: spherical shell

    Thank you! That was really helpful.
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    Electrostatics: spherical shell

    Electrostatics: spherical shell [SOLVED] Homework Statement A point charge Q_1 is located in the centre of a spherical conducting shell with inner radius a and outer radius b. The shell has total charge Q_2. Determine the electrostatic field \vec{E} and the potential \phi everywhere in...
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    QM: Magnus expansion, Gaussian integral

    Homework Statement The time-evolution operator \hat{U}(t,t_0) for a time-dependent Hamiltonian can be expressed using a Magnus expansion, which can be written...
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    Show that wave packet is an eigenstate to operator

    Show that wave packet is an eigenstate to operator [SOLVED] Homework Statement For a harmonic oscillator we can define the step up and down operators \hat{a} and \hat{a}^{\dagger} and their action as \hat{a}=\sqrt{\frac{m\omega}{2\hbar}}(\hat{x}+\frac{\imath}{m\omega}\hat{p}) \quad...
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    Nuclear physics: determine the date of the Chernobyl accident

    Thanks for you help! I got it right this time! :smile:
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    Nuclear physics: determine the date of the Chernobyl accident

    Homework Statement The acitvities from the fission products 131I and 133I were measured in the air of Gothenburg April 28 1986 at 17:00. The result was 0.12 Bq/m3 and 0.39 Bq/m3 for 131I and 133I respectively. These isotopes came from the Chernobyl nuclear reactor disaster. Use this...
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    Show Lorentz invariance for Euler-Lagrange's equations- how?

    I forgot to mention that my main problem is that I don't know how a Lorentz' transformation in generalized coordinates look like. I've only dealt with such in Cartesian coordinates (Google etc. doesn't help me out much at all with this).
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    Show Lorentz invariance for Euler-Lagrange's equations- how?

    Gigi: Thanks for your tip, but I don't think I can obtain that book soon enough. But maybe later. :-) samalkhaiat: Thank you! First of all I want to tell you that I am more or less a layman when it comes to this (I haven't studied natural sciences for almost three years, and I'm I only...
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    Show Lorentz invariance for Euler-Lagrange's equations- how?

    Hello, I need help showing that the Euler-Lagrange equations are Lorentz invariant (if Einstein's extended energy concept is used). Is there an easy way to show this? Any help would be very much appreciated.
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