Question

It takes time 8 min for light to reach from the sun to the earth surface. If speed of light taken to be 3 $\times$ 10${}^8$ ms${}^{-1}$, find the distance from the sun to the earth in km.

Answer 1

Given,

Time is taken by light to reach from the Sun to the Earth = 8 min = 480 s.
Speed of light = 3 × 10⁸ m/s

We know,
Distance from the Sun to the Earth = Speed × time

Putting all the values
= 3 × 10⁸ × 480 m

Or, = 1440 × 10⁸ m

To convert it into km

We can also write
= 1440 × 10⁸ × 10^-3 km
= 1440 × 10⁵ km
= 1.44 × 10⁸ km

Hence, the distance of the sun from the earth is 1.44 × ${10}^8$ km