MCQ : How many km are there in one light year?

Question

How many km are there in one light year?

1. 9.46 × 10¹⁵
2. 9.46 × 10¹²
3. 9.46 × 10⁹
4. 9.46 × 10⁶

Answer

9.46 × 10¹²

Explanation

To convert from light years to kilometres, we can use the speed of light as a conversion factor. The speed of light is approximately 299,792.458 kilometres per second. Therefore, we can calculate the distance in kilometres that light travels in one year as follows:

1 light year = (299,792.458 km/s) × (60 s/min) × (60 min/hr) × (24 hr/day) × (365.25 days/year)

Simplifying this expression, we get:

1 light year ≈ 9.46 × 10¹² km

Therefore, there are approximately 9.46 × 10¹² kilometres in one light year.