why kelvin is not expressed in degree?
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because both are the different unit.we have to convert it
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Each unit on this scale, called a Kelvin rather than a degree, is equal to a degree on the Celsius scale. For this reason, just the K, not the degree symbol, is used when reporting temperatures in Kelvin. There are no negative numbers on the Kelvin scale, as the lowest number is 0 K.
When you write a temperature using the Celsius, Fahrenheit, or Rankine scales, you include a degree symbol. Have you ever wondered why there is no degree in Kelvin?
The answer has to do with the definition of a degree. A degree is a change in temperature that is measured against a scale. The size of a degree is arbitrary. For example, originally the Celsius scale was set such that 0°C was the freezing point of water, while 100°C was the boiling point of water. Why water? Because it’s familiar and makes sense to people. But, the temperature scale could as easily have been designed around the freezing and boiling points of methane. You could even design your own temperature scale around what you consider to feel hot and cold. If you did so, your scale would use degrees. The old Celsius scale and your personal scale are examples of relative temperature scales. (Before you get all feisty… yes, the modern Celsius scale is based on absolute zero and the triple point of water, but there are still reasons why it uses degrees. We’ll get to that in a moment.)
Why Kelvin Doesn’t Have Degrees
Kelvin is different because it’s an absolute scale. 0K is absolute zero — the point at which gas molecules have no thermal energy. There’s no negative temperature on the Kelvin temperature scale. It’s not just about the endpoint, though. Temperature is a measure of the amount of energy contained by molecules. The Kelvin unit reflects this, where doubling the Kelvin temperature means you doubled the thermal energy.
A degree of the Celsius scale may seem like Kelvin, just bumped up 273, but if you double a Celsius temperature, you don’t double the thermal energy. Doubling 20°C gives you 40°C, which feels a lot hotter, but isn’t very meaningful from the thermodynamic perspective. Even worse, what if you double -40°C? Do you get -80°C or -20°C? You can see why scientific formulas often ask for Kelvin temperature.
When you write a temperature using the Celsius, Fahrenheit, or Rankine scales, you include a degree symbol. Have you ever wondered why there is no degree in Kelvin?
The answer has to do with the definition of a degree. A degree is a change in temperature that is measured against a scale. The size of a degree is arbitrary. For example, originally the Celsius scale was set such that 0°C was the freezing point of water, while 100°C was the boiling point of water. Why water? Because it’s familiar and makes sense to people. But, the temperature scale could as easily have been designed around the freezing and boiling points of methane. You could even design your own temperature scale around what you consider to feel hot and cold. If you did so, your scale would use degrees. The old Celsius scale and your personal scale are examples of relative temperature scales. (Before you get all feisty… yes, the modern Celsius scale is based on absolute zero and the triple point of water, but there are still reasons why it uses degrees. We’ll get to that in a moment.)
Why Kelvin Doesn’t Have Degrees
Kelvin is different because it’s an absolute scale. 0K is absolute zero — the point at which gas molecules have no thermal energy. There’s no negative temperature on the Kelvin temperature scale. It’s not just about the endpoint, though. Temperature is a measure of the amount of energy contained by molecules. The Kelvin unit reflects this, where doubling the Kelvin temperature means you doubled the thermal energy.
A degree of the Celsius scale may seem like Kelvin, just bumped up 273, but if you double a Celsius temperature, you don’t double the thermal energy. Doubling 20°C gives you 40°C, which feels a lot hotter, but isn’t very meaningful from the thermodynamic perspective. Even worse, what if you double -40°C? Do you get -80°C or -20°C? You can see why scientific formulas often ask for Kelvin temperature.
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