Kelvin (K)

Definition

The Kelvin (K) is the base unit of temperature in the International System of Units (SI). It is defined as one of the seven SI base units and is used to measure thermodynamic temperature. The Kelvin scale starts at absolute zero, the point at which all molecular motion ceases, and is defined as 0 K = -273.15 °C.

History

The Kelvin scale was proposed by Lord Kelvin (William Thomson) in 1848. It was developed to provide a consistent temperature scale based on absolute zero. The scale was officially adopted in the late 19th century, with the definition linked to the Celsius scale in 1954.

Uses

Kelvin is widely used in scientific research, engineering, and thermodynamics. It's essential in fields like physics, chemistry, and astronomy. For example, it is used in cryogenics, astrophysics, and to describe the color temperature of light sources.

Conversions

• 0 K = -273.15 °C (exact)
• 100 K = -173.15 °C
• 373.15 K = 100 °C (exact)

Fun Facts

• Kelvin is the only temperature scale that does not use the term "degree."
• A common misconception is that 0 K can be reached; in practice, achieving absolute zero is impossible due to the Third Law of Thermodynamics.