Question

One light year is_________

• A. $9.46\times$ ${10}^{12}km$
• B. $64\times$${10}^{12}km$
• C. $84.6\times$ ${10}^{12}km$
• D. $96.4\times$ ${10}^{12}km$

Answer 1

The correct option is A

$9.46\times$ ${10}^{12}km$

The distance traveled by light in one year in a vacuum is called one light year. The light travels at a speed of $3\times {10}^8$ meters per second. One light year is $9.46\times$ ${10}^{12}km$. It is used as a unit to measure astronomical distances.

One light year = Number of days in a year$\times$Number of hours in a day$\times$Number of seconds in a day$\times$Speed of light

= $365\times 24\times 3600\times 3\times {10}^8$ = $9.46\times {10}^{15}m$ = $9.46\times {10}^{12}km$