Meter

Definition

A meter is the fundamental unit of length in the International System of Units (SI). It is defined as the distance light travels in a vacuum in 1/299,792,458 seconds.

5 Must Know Facts For Your Next Test

1. The meter is the base unit of length in the SI system.
2. It was redefined in 1983 based on the speed of light in a vacuum.
3. One meter equals 100 centimeters or 1000 millimeters.
4. Common instruments to measure meters include rulers, tape measures, and laser distance meters.
5. The original definition was based on a fraction of the Earth's meridian but has since evolved to be more precise.

Review Questions

• What is the current definition of a meter based on?
• How many centimeters are there in one meter?
• Why was the definition of a meter changed from its original form?

Related terms

Second:

The base unit of time in the International System of Units (SI), defined by taking the fixed numerical value of the cesium frequency.

Kilogram:

The base unit of mass in SI, currently defined by setting Planck's constant exactly to $6.62607015 \times 10^{-34}$ joule-seconds.

Speed of Light:

$299,792,458$ meters per second, used to define a meter and considered a fundamental constant in physics.