Question

Define light year.

Answer 1

1. A light-year is defined as the distance traveled by light in one year.
2. We know that speed of light$,v=3\times {10}^{8}m/s$
3. Time,$t=365days$ $=365\times 24\times 60\times 60second$
4. Also, we know that $dis\tan ce=speed\times time$$=vt=3\times {10}^8\times 365\times 24\times 60\times 60m$ $=9.46\times {10}^{15}meters.$
5. Hence one light-year is equal to $9.46\times {10}^{15}m$.