Kelvin facts for kids
Quick facts for kids Kelvin |
|
|---|---|
Lord Kelvin
|
|
| General information | |
| Unit system | SI base unit |
| Unit of | Temperature |
| Symbol | K |
| Named after | William Thomson, 1st Baron Kelvin |
The kelvin (symbol: K) is the official unit of temperature in the SI (which is like the world's standard measurement system). It's a special way to measure how hot or cold something is. The Kelvin scale is named after a brilliant scientist from Belfast, William Thomson, 1st Baron Kelvin (1824–1907). He was an engineer and physicist who taught at Glasgow University. He believed we needed an "absolute" way to measure temperature.
Unlike Fahrenheit or Celsius scales, you don't say "degree Kelvin." You just say "kelvin." For example, you'd say "77 kelvins," not "77 degrees Kelvin."
Contents
What is Kelvin?
The Kelvin scale is unique because it starts at the lowest possible temperature, called absolute zero. At absolute zero, particles (like atoms and molecules) stop moving completely. This means there are no negative temperatures on the Kelvin scale.
Scientists use the Kelvin scale a lot, especially in fields like physics and chemistry. This is because it directly relates to how much energy particles have. The hotter something is in kelvins, the more energy its particles have.
Why is it Special?
The Kelvin scale is an "absolute temperature scale." This means its zero point (0 K) is the coldest anything can ever get. This is different from Celsius or Fahrenheit, where zero is just a point on the scale, not the absolute coldest.
For example, water freezes at 0 degrees Celsius, but that's 273.15 kelvins. The idea behind Kelvin is that the pressure of a gas is directly related to its temperature in kelvins. If you double the temperature of a gas in kelvins, its pressure will also double (if the volume stays the same).
How Kelvin is Defined
For a long time, the Kelvin scale was linked to the freezing and boiling points of water. However, on November 16, 2018, scientists changed its official definition. Now, the kelvin is defined using a fixed value of something called the Boltzmann constant.
The Boltzmann constant is a fundamental number in physics that helps describe the energy of particles at a certain temperature. This new definition makes the kelvin even more precise and stable. This change officially started on May 20, 2019.
Related pages
Images for kids
-
An ice water bath was used to help set up thermometers in the past.
-
Lord Kelvin, the scientist who gave his name to the kelvin unit.
See also
In Spanish: Kelvin para niños
