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Explore the simplified solutions in Electrodynamics through the introduction of potentials and gauge transformations. Learn about the equations for retarded potentials, inhomogeneous wave equations, and spherical waves. Discover the use of Green's function, Lienard-Wiechert potentials, and EM waves radiated by moving point charges.
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10. Potentials and Fields Introduction of potential V substantially simplifies finding solutions of problems in Electrostatics. Does such a simplification exist for Electrodynamics as well? Yes, it does: The retarded potentials
Coulomb Gauge Used in electro- and magnetostatics Lorentz Gauge Used in electrodynamics Will be used further on.
Equations for the retarded potentials Inhomogeneous wave equations.
Spherical waves Another, very common solution of the wave equation: Example: sinusoidal spherical wave
Sound waves from a telephone hand set spreading out in air. The waves have been made visible by sweeping out the space in front of the hand set with a light source whose brightness is controlled by a microphone. Circular wavefronts diverging from a point Source in a ripple tank.
Green’s Function Very short and intense pulse:
Be careful, the retarded time introduces a new and complicated dependence of Retarded Potentials
The field of a moving point charge field attached to the charge radiated EM wave