/electric-field-moving-charge

Primary LanguageMATLAB

Animation of the Electric Field of a Moving Charge

MATLAB animation of the evolution of the electric field of a moving charge, which is the derivative of the retarded potential or Liénard–Wiechert potential.

The project is initiated for a visualization and intuitive understanding of related physics concepts after completing the undergraduate course Electromagnetics (by Qing Wang) in Jun, 2012, and is modified in Dec., 2012 for a MATLAB course.

Details:

  • Animation is implemented by the getframe and movie APIs in MATLAB, where the first captures and saves each frame of the electric field at each moment, which is plotted by the streamline API, and the second animates the stored frames.

  • "doc.pdf": the document detailing related physics theory, algorithms and implementations (in Chinese).

  • "ElecField.m": the main file for implementation and execution.

  • "NewSubs.m": auxiliary file for extending the built-in subs function to return an array (instead of a scalar) when the to-be-substituted function is constant.

Usage:

Run ElecField(T, type, k) in the MATLAB console, where:

  • T is the lasting time of the animation;
  • type is the type of the motion of the charge (currently supports 'line', 'harmonic', and 'circle');
  • k is the ratio of the maximum moving speed against the speed of the light (taken as 1).

The following is a snapshot at some moment during running ElecField(10, 'harmonic', 0.8). demo-harmonic