Answer
The meter is the fundamental unit of length in the International System of Units (SI). Its definition has changed over time, and there have been several earlier definitions of the meter.
The origin of the meter can be traced back to the French Revolution when the French Academy of Sciences was tasked with creating a new system of measurements based on natural phenomena. The initial definition of the meter was based on the length of a pendulum with a half-period of one second at a standard gravitational acceleration. This definition was later revised to be based on the length of a prototype meter bar made of platinum-iridium alloy.
In 1960, the 11th General Conference on Weights and Measures defined the meter as "the length equal to 1650763.73 wavelengths in vacuum of the radiation corresponding to the transition between the 2p10 and 5d5 quantum levels of the krypton-86 atom." This definition was based on the wavelength of a specific atomic transition and provided a highly precise and stable definition of the meter.
In 1983, the definition of the meter was further refined to be "the length of the path travelled by light in a vacuum during a time interval of 1/299 792 458 of a second." This definition is based on the speed of light, which is a fundamental constant of nature and provides a highly accurate and reproducible definition of the meter.
Compared to earlier definitions, the present definition of the meter based on the speed of light has several advantages. First, it is based on a fundamental constant of nature and is not subject to changes in physical phenomena or material artifacts over time. This provides a highly stable and reliable definition of the meter that can be reproduced anywhere in the world. Second, the definition based on the speed of light is highly precise and accurate, allowing for precise measurements in a wide range of applications. Finally, the definition based on the speed of light is easily accessible and understandable, making it easier to teach and learn about the meter and its properties.
Work Step by Step
The meter is the fundamental unit of length in the International System of Units (SI). Its definition has changed over time, and there have been several earlier definitions of the meter.
The origin of the meter can be traced back to the French Revolution when the French Academy of Sciences was tasked with creating a new system of measurements based on natural phenomena. The initial definition of the meter was based on the length of a pendulum with a half-period of one second at a standard gravitational acceleration. This definition was later revised to be based on the length of a prototype meter bar made of platinum-iridium alloy.
In 1960, the 11th General Conference on Weights and Measures defined the meter as "the length equal to 1650763.73 wavelengths in vacuum of the radiation corresponding to the transition between the 2p10 and 5d5 quantum levels of the krypton-86 atom." This definition was based on the wavelength of a specific atomic transition and provided a highly precise and stable definition of the meter.
In 1983, the definition of the meter was further refined to be "the length of the path travelled by light in a vacuum during a time interval of 1/299 792 458 of a second." This definition is based on the speed of light, which is a fundamental constant of nature and provides a highly accurate and reproducible definition of the meter.
Compared to earlier definitions, the present definition of the meter based on the speed of light has several advantages. First, it is based on a fundamental constant of nature and is not subject to changes in physical phenomena or material artifacts over time. This provides a highly stable and reliable definition of the meter that can be reproduced anywhere in the world. Second, the definition based on the speed of light is highly precise and accurate, allowing for precise measurements in a wide range of applications. Finally, the definition based on the speed of light is easily accessible and understandable, making it easier to teach and learn about the meter and its properties.
