A LASER is source of very intense, monochromatic and unidirectional beam of light These properties of a laser light can be exploited to measure long distances

A LASER is source of very intense, monochromatic and unidirectional beam of light These properties of a laser light can be exploited to measure long distances. The distance of moon from earth has been already determined very precisely using a laser as a source of light. A laser light beam at the moon takes 2.56 sec, to return after reflection at the moon’s surface. How much is the radius of lunar orbit around the earth ?