Question

How do you convert kelvin to Celsius and vice versa?

Answer 1

Hint: Kelvin and Celsius both are temperature measurement units which are related by the numerical value of $273.15$ . Recall the physical conditions like freezing of water, boiling of water, ideal thermodynamic condition and analyse what values each of these units hold at those physical state.

Complete step by step answer:
Kelvin and Celsius are the two most important and widely used temperature measurements units around the world.
Kelvin is the SI unit of temperature. It is used in colour temperature determination and in lighting applications. 0 Kelvin or 0 K is considered to be an ideal thermodynamic condition where all entropies become zero.
Celsius scale is the centigrade scale. It is developed on the freezing point and boiling point of water. 0 degrees Celsius reflects freezing point of water and 100 degrees Celsius reflects boiling point of water. It is a derived SI unit of temperature. It is a commonly used scale to measure temperature.
When we talk about conversion of the units between Kelvin and Celsius, the numeric value of $273.15$ plays an important role. We know that 0 Celsius denotes $273.15K$ and 0 Kelvin denotes ${273.15^ \circ }C$ . So from this observation we can derive a relation between Kelvin and Celsius as follows,
$Kelvin = Celsius + 273.15$
Or
$K{ = ^ \circ }C + 273.15$
The same relation can be written in terms of Celsius as,
$Celsius = Kelvin - 273.15$
Or
$^ \circ C = K - 273.15$
So the above two relations are the required expressions used to convert Kelvin to Celsius and vice versa.

Note: Kelvin and Celsius are precisely the same. They both are nine-fifth the size of a degree Fahrenheit. The conversion of Kelvin to Fahrenheit can be achieved by subtracting $273.15$ , multiplying by 5 and then finally adding 5. The same can be done for Celsius just be adding $273.15$ instead of subtracting.