An oscillating electric dipole p = p₀cos(ωt) ẑ radiates electromagnetic waves. The angular power distribution is:
Maximum radiation is perpendicular to the dipole axis; zero radiation along the axis. Total power:
The sin²θ "donut" pattern is fundamental to antenna theory (half-wave dipole antenna), Rayleigh scattering (why sky is blue: ω⁴ → shorter wavelengths scatter more), and atomic spontaneous emission.