Question

The speed of light in vaccum is 3 × 10⁸ m/s. Sunlight takes about 8 minutes to reach the earth. Express distance of Sun from Earth in standard form.

Answer 1

It is given that,

Speed of light = 3 × 10⁸ m/s

Time taken by light to reach the Earth = 8 min

= 8 × 60 s  ......[∴ 1 min = 60s]

= 480 s 

We know that,

Distance = Speed × Time

= 3 × 10⁸ × 480

= 1440 × 10⁸ 

= 1.440 × 10³ × 10⁸   ......[∴ 10³ × 10⁸ = 10¹¹]

= 1.44 × 10¹¹ 

Hence, the distance of Sun from the Earth is 1.44 × 10¹¹ m.