Question

How is the velocity of light used for determining the standard metre?

Answer 1

Velocity of the ;light in air or Vacuum = 3 × 10⁸ m/s. 

Originally it is about, 299792000 m/s. 

For the convenience, We used to take the value as 3 × 10⁸ m/s. 

Although, For determine the  definition of the meter, correct speed of the light is taken. 


In 1960, Eleventh General conference of the International Bureau of Weight and Measures defined the meter as ⇒ 

1 meter is defined as the distance travelled by the light in 1/299792000 s. 


Determining the definition of meter is useful as the comparison become easy. Also, the problems of the Increase in temperature results in expansion for the meter rod is avoided in standard meter. 


Hope it helps.