What is the SI base unit for length?

What is the SI base unit for length?

• A. Kelvin (K)
• B. Meter (m)
• C. Kilogram (kg)
• D. Second (s)

Answer: (B)

Length is defined by a base unit in the SI system called the meter. The meter is fixed by the speed of light, so one meter is the distance light travels in vacuum in 1/299,792,458 of a second. This makes the unit precise and universally reproducible. The other options correspond to different physical quantities: Kelvin is for temperature, the kilogram is for mass, and the second is for time. In everyday use we still express length in meters or in multiples/submultiples of a meter (like centimeters or kilometers), all rooted in this base unit.

Length is defined by a base unit in the SI system called the meter. The meter is fixed by the speed of light, so one meter is the distance light travels in vacuum in 1/299,792,458 of a second. This makes the unit precise and universally reproducible. The other options correspond to different physical quantities: Kelvin is for temperature, the kilogram is for mass, and the second is for time. In everyday use we still express length in meters or in multiples/submultiples of a meter (like centimeters or kilometers), all rooted in this base unit.