Recent content by andrew1982

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    Liouville's Theorem: Sketching Rectangle Motion in px-x Plane

    But it was a constant force, not an oscillator, right? It was some time ago that I did these things, but an approach could be to solve the equations of motion for x and px and then use the corners of the rectangle in phase space as starting conditions for 4 different trajectories. Then you can...
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    Jackson Electrodynamics problem 9.8a

    Hi thanks a lot for the link! Very useful website :) Ok, so my understanding after reading this solution is that the electromagnetic angular momentum that is radiated to infinity in time dt is contained in a spherical shell with radius r->inf. and thickness dr=c dt. So dL/dt is obtained by...
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    Simple problem on waves (Math query)

    Hi! OK, explicitly I think your integral would be (ignoring the first constant): \int\frac{\partial g_{I}(-v_{1}t)}{\partial t}dt= \int -v_1\, g'_I(-v_{1}t)dt using the chain rule (yes if you want to write out the detalis we need it). Now putting x=-v1 t, and with dt=-dx/v1 =\int -v_1\...
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    Simple problem on waves (Math query)

    Maybe I'm wrong, but I don't think you need to use the chain rule. Since you have no hidden t dependence in your functions I guess you can say \int (\frac{\partial}{\partial t} f(z,t) )dt=f(z,t) + C Differentiation and then integration with respect to t should give the same function back...
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    When will the LHC be ready to power up its first collision?

    maybe at the end of this year or the next..
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    Jackson Electrodynamics problem 9.8a

    Homework Statement 9.8a) Show that a classical oscillating eletric dipole p with fields given by (9.18) radiates electromagnetic angular momentum to infinity at the rate \frac{d\mathbf{L}}{dt}=\frac{k^3}{12\pi\epsilon_0}\textrm{Im}[\mathbf{p^*\times p}] Hint: The electromagnetic angular...
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    Jackson Electrodynamics problem 6.5b

    Thanks for your replies, it was very helpful! Using section 5.6 of Jackson as you said I saw that I could show directly that the first integral {\bf P_{field}}=-\frac{1}{c^2} \int {\bf (E(0)\cdot x) J)} d^3x is equal to the sought answer without using the abc vector rule. Looking below eq...
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    Jackson Electrodynamics problem 6.5b

    Homework Statement A localized electric charge distribution produces an electrostatic field, {\bf E}=-\nabla \phi Into this field is placed a small localized time-independent current density J(x) which generates a magnetic field H. a) show that the momentum of these electromagnetic...
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