Given that the distance traveled by light is d = 3 km = 3000 m.
Also, the speed of light is
[tex]c=\text{ 3}\times10^8\text{ m/s}[/tex]We have to find the time taken by light to travel.
The time taken can be calculated by the formula
[tex]\begin{gathered} \text{speed = }\frac{dis\tan ce}{time} \\ \text{time =}\frac{dis\tan ce\text{ }}{speed} \\ =\frac{d}{c} \end{gathered}[/tex]Substituting the values, the time will be
[tex]\begin{gathered} t=\frac{3000}{3\times10^8} \\ =1\times10^{-5}\text{ seconds} \end{gathered}[/tex]