Light is shining perpendicularly on the surface of the earth with an intensity of 680 W/m2. Assuming that all the photons in the light have the same wavelength (in vacuum) of 681 nm, determine the number of photons per second per square meter that reach the earth.

Asatellite with an orbital period of exactly 24.0 h is always positioned over the same spot on earth. this is known as a geosynchronous orbit. television,communication, and weather satellites use geosynchronous orbits. at what distance would a satellite have to orbit earth in order to have a geosynchronous orbit?