일반물리학 2 — Electromagnetic Waves: Problem 48

48 Assume (unrealistically) that a TV station acts as a point source broadcasting isotropically at 3.0 MW. What is the intensity of the transmitted signal reaching Proxima Centauri, the star nearest our solar system, 4.3 ly away? (An alien civilization at that distance might be able to watch X Files.) A light-year (ly) is the distance light travels in one year.