UPSC NDA I 2021 General Ability Solved Paper

CONCEPT:
- Length is a measure of the size or distance between two points. The SI unit of length is the meter (m).
- Light year: It is the distance travelled by light in one year.
- A light-year is a convenient unit of measurement of large distances.
- Generally, a light-year is used to represent astronomical distances.
- One light-year is approximately 9 trillion (9×1012)km.
EXPLANATION:
- A light-year is a unit of length. Therefore option 4 is correct.
- It is the distancetravelled by light in a vacuum in one year.
- A light-year is used in astronomy to measure the distances of nearby stars.
⇒1‌ light-year ‌=11y=9.467×1015m