Respuesta :

4 Earth years. I hope this helps

Given:

Distance of alpha century = 4 light year

Speed of light = 3 × [tex] 10^{8} [/tex] m

To find:

Time taken by light to reach earth = ?

Formula used:

Distance = speed × time

Solution:

Distance = 4 light year

Converting distance from light year into meter

1 light year = 365 × 24 × 60 × 60

4 light year = 4 × 365 × 24 × 60 × 60× 3 ×[tex] 10^{8} [/tex]

As we know,

Distance = speed × time

s = v × t

Where s = distance

v = velocity

t = time

So,t = [tex] \frac{s}{v} [/tex]

t = [tex] \frac{4 × 365 × 24 × 60 × 60× 3 ×[tex] 10^{8} [/tex]}{3 ×[tex] 10^{8}} [/tex]

t = 4 × 365 × 24 × 60 × 60 second

t = 4 year

Thus, Time taken by light to reach earth from alpha century is 4 earth year.