The Total solution for NCERT class 6-12
A LASER is a source of very intense, monochromatic, andunidirectional beam of light. These properties of a laser light can beexploited to measure long distances. The distance of the Moon from the Earthhas been already determined very precisely using a laser as a source of light.A laser light beamed at the Moon takes 2.56 s to return after reflection at theMoonтАЩs surface. How much is the radius of the lunar orbit around the Earth?
Time taken by the laser beam to return to Earth after reflectionfrom the Moon = 2.56 s
Speed of light = 3 ├Ч 108┬аm/s
Radius of the lunar orbit = Distance between the Earth and theMoon = 1.28 ├Ч 3 ├Ч 108┬а= 3.84 ├Ч 108┬аm = 3.84 ├Ч105┬аkm