Question

How much time does light from the sun take to reach earth? (Given distance between sun and earth = $1.51\times {10}^8$ km)

• A. 5 minutes 30 seconds
• B. 8 minutes 22 seconds
• C. 10 minutes 40 seconds
• D. 1 minute

Answer 1

The correct option is B 8 minutes 22 seconds

We know that the speed of light is $3\times {10}^5$ km/s. Therefore, to find the time taken by light to reach earth we use the distance-time formula:

$d=vt$
$t=\frac{1.51\times {10}^8}{3\times {10}^5}=503sec$

Which amounts to 8 minutes and 22 seconds