Department of Pre-University Education, KarnatakaPUC Karnataka Science Class 11

# The metre is defined as the distance travelled by light in 1/(299,792,458) second. Why didn't people choose some easier number such as  1/(300,000,000) second? Why not 1 second? - Physics

The metre is defined as the distance travelled by light in 1/(299,792,458) second. Why didn't people choose some easier number such as  1/(300,000,000) second? Why not 1 second?

#### Solution

The speed of light in vacuum is 299,792,458 m/s.
Then time taken by light to cover a distance of 1 metre in vacuum =1/(299 ,792 ,458 S
Hence, the metre is defined as the distance travelled by light in 1/(299, 792, 458) S

As 300,000,000 m/s is an approximate speed of light in vacuum, it cannot be used to define the metre.

The distance travelled by light in one second is 299,792,458 m. This is a large quantity and cannot be used as a base unit. So, the metre is not defined in terms of second.

Concept: Physics Related to Technology and Society
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#### APPEARS IN

HC Verma Class 11, Class 12 Concepts of Physics Vol. 1
Chapter 1 Introduction to Physics
Short Answers | Q 1 | Page 8

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