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.

Explanation

Here,`x =10^(13) km = 10^(16)m`
Velocity of laser beam, `c =3xx10^8m//s`
As `x = (cxxt)/(2) :. t= (2x)/(c ) = (2xx10^(16))/(3xx10^8) s = 6.67xx10^7s`