Question

The distance of nearest star from earth is 10^13 km. Calculate the time taken by a laser beam to return to earth after
reflection from the star.

Answer 1

Explanation:

distance to the nearest star = 10^13 km = 10^16 m

speed of light =3×10^8 m/s

= 299792 km/s

total distance = 2×10^16 m

total time take = total distance / speed of light

= 2×10^16 / 3×10^8

= 6.66×10^7 s