Question

How much time a light ray take to reach from earth to moon?
(Distance of moon from the earth $= 3.5 \times 10^{8}\, m)$

• A. $2\,s$
• B. $1.4 \, s$
• C. $8\, min$
• D. $1.16 \, s$

Answer 1

Answer: (D)

Here,
Speed of light, $c = 3 \times 10^8\, ms^{-1}$
Distance of moon from the earth, $D = 3.5 \times 10^8\, m$
Time taken by the light to reach from earth to moon is
$t=\frac{D}{c}=\frac{3.5 \times 10^{8}\,m}{3 \times 10^{8}\,ms^{-1}}$
$=1.16\,s$