Results 1 - 10 of 837
Results 1 - 10 of 837. Search took: 0.022 seconds
|Sort by: date | relevance|
[en] The Rutherford scattering of a classical point charge moving in an attractive field and obeying the Lorentz-Dirac equation is solved. The size of the spatial part of the incoming 4-velocity (γ2-1)1/2 takes the values 1000, 100 and 0.1, respectively. Asymptotic expansions of physical solutions are derived and used. Results are displayed and discussed. It is shown that all solutions satisfy physical expectations. A condition for treating radiation reaction as a perturbation is applied. Some earlier problems that have led to suggestions of unphysical features of the Lorentz-Dirac equation are explained on a physical basis. (author)
[en] In discussing radiation from multiple point charges or magnetic dipoles, moving in circles or ellipses, a variety of Kapteyn series of the second kind arises. Some of the series have been known in closed form for a hundred years or more, others appear not to be available to analytic persuasion. This paper shows how 12 such generic series can be developed to produce either closed analytic expressions or integrals that are not analytically tractable. In addition, the method presented here may be of benefit when one has other Kapteyn series of the second kind to consider, thereby providing an additional reason to consider such series anew
[en] In textbooks the pictures of exact and approximate equi-potentials and the lines of force of a dimensional electric point dipole are usually presented without mentioning the equation of lines of force. Generally, these pictures are generated by numerical methods. Smythe  provides a special method to obtain an involved expression for it, but in this letter we show that the usual and well-known approximation to the potential V∼2Ka cos θ/r2 due to two point charges (±q) separated by a distance a itself poses a more simply solvable problem that yields a simple expression for lines of force. (letters and comments)
[en] We consider the longitudinal point-charge wakefield, w(s), for an axisymmetric collimator having inner radius b, outer radius d, inner length g, and taper length L. The taper angle α is defined by tan α = (d-b)/L. Using the electromagnetic simulation code ECHO, we explore the dependence of the wakefield on a collimator's geometric parameters over a wide range of profiles: from small-angle tapers to step-function transitions. The point-charge wakefield is determined using an approximation introduced by Podobedov and Stupakov. We have found it useful to exhibit the wakefield as a function of the scaled variable s/dα. For small taper angles, our results illustrate the satisfaction of the longitudinal scaling found by Stupakov, Bane, and Zagorodnov; and for larger taper angles, the breaking of this longitudinal scaling is clearly depicted. The use of the scaled variable s/dα turns out to be especially well suited to describing the wakefield for a collimator with step-function profile (α = π/2).
[en] A relation is established between the prepotential of the supersymmetric N = 1 electrodynamics and the supersymmetric current of a point charge. A solution is found for the prepotential corresponding to a static charge. It is shown that in the Wess-Zumino gauge the latter describes two physical fields. The first is the field of a particle with charge e and magnetic moment (e/2mc) xisigmaxi-bar, where xi/sup α/ and xi-bar/sup alpha-dot/ are the Grassmann coordinates of the charge. The second is the field of a ''Grassmann dipole.''
[en] We investigate the possible existence of nonradiating motions of systems of point charges, according to classical electrodynamics with retarded potentials. We prove that two point particles of arbitrary electric charges cannot move for an infinitely long time within a finite region of space without radiating electromagnetic energy. We show however with an example that nonradiating accelerated motions of systems of point charges do in general exist
[en] Doubts have been expressed in a comment about the tenability of the formulation for radiative losses in our recent published work (Singal 2016 Eur. J. Phys. 37 045210). We provide our reply to the comment. (reply)