All Problems

Electromagnetic Waves. Radiation

Problem 4.220

The mean power radiated by an elementary dipole is equal to \(P_{0}\). Find the mean space density of energy of the electromagnetic field in vacuum in the far field zone at the point removed from the dipole by a distance \(r\) along the perpendicular drawn to the dipole's axis.

Reveal Answer
w=3/8P0/πr2c\langle w\rangle=3 /{ }_{8} P_{0} / \pi r^{2} c