The kelvin scale - how could it have been defined?

In summary, the kelvin scale uses the absolute zero as its null point, but also needs a second point to define a linear scale. The triple point of water is used because it provides better accuracy compared to using the freezing and boiling points of water, which are inherited from the Celsius scale. This decision was made in the 1960s by the International Bureau of Weights and Measures.
  • #1
spaghetti3451
1,344
33
Hey,

I know that the kelvin scale uses the absolute zero as its null point. If so, I wonder why the scale needs to be defined using the triple point of water. I mean, the absolute zero serves the purpose of defining the kelvin scale already, doesn't it?
 
Physics news on Phys.org
  • #2
You must have two points to define linear scale, not just one.
Celsius used freezing and boiling points of water. Kelvin found one, being fundamental, but still needs the second.
 
  • #3
I was under the impression that the size of a degree Kelvin was defined to be the same as a degree Celcius. If that is true then you would only need a single "base" temperature.
 
  • #4
Those two approaches are equivalent, with respect to accuracy.

We may obtain better accuracy using just one point (tripple point of water) than using inherited after Celsius distance between two points (melting and boiling of water at the 1bar pressure), which depend in turn on accuracy of our definition of pressure unit.
 
  • #5

1. What is the Kelvin scale?

The Kelvin scale is a temperature scale used in science that starts at absolute zero, the lowest possible temperature, and is based on the properties of gases.

2. How is the Kelvin scale different from other temperature scales?

The Kelvin scale is different from other temperature scales because it is an absolute scale, meaning it has no negative values and is based on the fundamental properties of matter. This makes it more accurate and precise for scientific measurements.

3. Who is responsible for defining the Kelvin scale?

The Kelvin scale was defined by Irish physicist William Thomson, also known as Lord Kelvin, in the 19th century. He proposed the scale based on the work of other scientists and his own experiments.

4. How was the Kelvin scale defined?

The Kelvin scale was defined using the properties of gases, specifically the ideal gas law which states that at constant pressure, the volume of a gas is directly proportional to its temperature. Lord Kelvin used this law to define the scale, with 0 Kelvin being absolute zero and equal to -273.15 degrees Celsius.

5. Why was the Kelvin scale chosen as the standard unit for temperature in scientific measurements?

The Kelvin scale was chosen as the standard unit for temperature in scientific measurements because it is an absolute scale that is based on the fundamental properties of matter. This makes it more accurate and precise for scientific experiments and allows for easier conversion between different temperature scales.

Similar threads

  • Introductory Physics Homework Help
Replies
20
Views
4K
Replies
3
Views
2K
Replies
3
Views
839
Replies
1
Views
415
Replies
9
Views
337
Replies
7
Views
783
Replies
15
Views
2K
  • Thermodynamics
2
Replies
40
Views
7K
  • Thermodynamics
Replies
9
Views
2K
  • Other Physics Topics
Replies
9
Views
5K
Back
Top