Question

The distance of a galaxy is 5·6 × 10²⁵ m . Assuming the speed of light to be 3 × 10⁸ `"ms"^-1`. Find the time taken by light to travel this distance . 
[Hint : `"Time taken" = "Distance travelled"/"speed"`]

Answer 1

Distance of galaxy = 5.6 × 10²⁵ m

Speed of light = 3 × 10⁸ m/s

`"Time taken by light" = "Distance travelled"/"speed of light"`

= `((5.6 × 10^25)/ (3 × 10^8))` s

= 1.87 × 10¹⁷ s