Question

One light-year is used for the measurement of large distances?
a) True
b) False

Answer 1

One light-year is defined as the distance traveled by light in one year in a vacuum. A light-year is a unit of distance. It is the distance that light can travel in one year. Light moves at a velocity of about 300,000 kilometers (km) each second.

Complete step by step answer:
As we know that the speed of light is $3\times {{10}^{8}}m{{s}^{-1}}$
So, the distance covered by light in 1 second is: $3\times {{10}^{8}}m$
Now, we need to find the distance covered in 1 year.
So, time of 1 year is:
$\begin{aligned} & \text{=365 days }\\!\\!\times\\!\\!\text{ 24 hrs }\\!\\!\times\\!\\!\text{ 60min }\\!\\!\times\\!\\!\text{ 60sec} \\\ & \text{=31536000 sec} \\\ \end{aligned}$
So, the distance covered in 1 year is:
$\begin{aligned} & =31536000\times 3\times {{10}^{8}} \\\ & =9.46\times {{10}^{15}}m \\\ \end{aligned}$
The distance itself is greater than the circumference of earth. Therefore, this measurement is used for large distances.

So, the correct answer is “Option A”.

Note:
A light-year is a unit of distance. It is the distance that light can travel in one year. For most space objects, we use light-years to describe their distance. So in one year, it can travel about 10 trillion km. Moreover if we will see a one light year is also equal to 9,500,000,000,000 km.