Question

Derive an expression for the electromagnetic field due to an oscillating dipole

Answer 1

   Animation shows the electric field lines due to an electric dipole oscillating vertically at the origin. Near the dipole, the field lines are essentially those of a static dipole leaving a positive charge and ending up at a negative charge. However, at a distance of the order of half wavelength (lambda = 2Pi is assumed here) or greater, the field lines are completely detached from the dipole. This detachment characterizes radiation fields which propagate freely (without being attached to charges) in free space at the speed c.