To convert Kelvin to Celsius, you can use the following formula: Celsius = Kelvin – 273.15. This conversion formula is based on the fact that the freezing point of water in Celsius is 0 degrees, while in Kelvin it is 273.15 K. Similarly, the boiling point of water in Celsius is 100 degrees, while in Kelvin it is 373.15 K. Therefore, 90 Kelvin would be equivalent to -183.15 degrees Celsius.

Kelvin and Celsius are both temperature scales, with Kelvin being the absolute temperature scale and Celsius being a relative temperature scale. In scientific and engineering contexts, Kelvin is often used due to its direct relation to the kinetic energy of particles. It is important to note that 0 Kelvin is absolute zero, the coldest possible temperature, where all molecular motion ceases.

For example, if you have a temperature of 300 K and you want to convert it to Celsius, you would use the formula: Celsius = 300 K – 273.15 = 26.85 degrees Celsius. This allows for easy conversion between the two scales, especially in scientific and academic settings.

In conclusion, 90 Kelvin is equal to -183.15 degrees Celsius. Understanding the conversion between these two temperature scales is important in various scientific and engineering disciplines, and the conversion formula allows for easy and accurate calculations.