What is the SI unit of temperature?

Kelvin

The correct answer is option 1. Kelvin.

The Kelvin (K) is the base unit of temperature in the International System of Units (SI). Named after the Scottish physicist William Thomson, 1 Kelvin is defined as the fraction 1/273.16 of the thermodynamic temperature of the triple point of water. The triple point is a thermodynamic state at which water coexists in three phases: solid, liquid, and gas.

Here is a brief explanation:

1. Absolute Temperature:

Kelvin is an absolute temperature scale, meaning it starts from absolute zero (0 K), which is the lowest possible temperature where particles have minimal thermal motion.

2. Conversion from Celsius:

The Kelvin scale is directly related to the Celsius scale. The Kelvin temperature (T) is obtained by adding 273.15 to the Celsius temperature (t): \( T(K) = t(°C) + 273.15 \).

3. No Negative Temperatures:

Unlike the Celsius and Fahrenheit scales, the Kelvin scale does not use negative values. Zero Kelvin represents absolute zero, the point at which a substance would have minimal thermal energy.

4. Standard Unit in Science:

Kelvin is the standard unit of temperature in scientific contexts, especially in physics and chemistry. It is often used in scientific research, engineering, and various other disciplines.

5. SI Unit:

The International System of Units (SI) recognizes the Kelvin as the unit of temperature, and it is widely used in scientific literature, research papers, and everyday scientific measurements.

In summary, Kelvin is the SI unit of temperature, providing a scale that begins from absolute zero and is commonly used in scientific and engineering applications where precise temperature measurements are essential.