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 distance. The distance of the moon from the Earth has been already determine very precisly at the moon's surface. How much is the radius of the lunar orbit around the Earth?
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We known that speed of laser light `= c = 3xx10^(8) m//s`. If d be the distance of Moon from the earth, the time taken by laser signal to return after reflection at the Moon's surface <br> `t=2.56 s=(2d)/c=(2d)/(3xx10^(8) ms^(-1))` <br> `implies d=1/2xx2.56xx3xx10^(8) m=3.84xx10^(8) m`.