The SI unit of length is the metre (m). It is defined as the length of the path travelled by light in vacuum during a time interval of 1/299,792,458 of a second. This definition links the metre to the fixed numerical value of the speed of light in vacuum, ensuring a precise and constant standard for length measurement
. In summary:
- Unit: metre
- Symbol: m
- Definition: Distance light travels in vacuum in 1/299,792,458 seconds
