Question

A lightyear is a unit of distance. It is the distance travelled by light in one year. If the speed of light is equal to 3 x ${10}^8$m/s, how many kilometres will make up 1 light year?

• A. 946 x km
• B. 1.095 x km
• C. 1095 km
• D. 9.46 x km

Answer 1

Answer: (C), (D)

The correct options are
C

1095 km

D

9.46 x km

1 light year = speed of light $\times$ time

= $3\times {10}^{8}m/s\times 365\times (24\times 60\times 60)s$

= $9.46\times {10}^{15}m$ (approx)

= $9.46\times {10}^{12}km$ (approx) or $94.6\times {10}^{11}km$ (approx)