Measurement of Temperature- Celsius, Fahrenheit & Kelvin scales


Celsius scale

  1. Celsius is the common unit of measuring temperature, termed after Swedish astronomer, Anders Celsius in 1742, before that it was known as Centigrade as thermometers using this scale are calibrated from 0°C to 100°C (in Greek, Centium means 100 and Gradus means steps, both words make it centigrade and later Celsius)
  2. One Kelvin is one degree Celsius. Temperature in Celsius scale can be easily converted to Fahrenheit and Kelvin scale as discussed ahead.

Fahrenheit Scale

  1. Common unit to measure human body temperature. It is termed after name of German Physicist Daniel Gabriel Fahrenheit. Freezing point of water taken as 32*F and boiling point 212*F. Thermometers with Fahrenheit scale are calibrated from 32*F to 212*F. Relation between Fahrenheit scale and Celsius scales is as under.Fahrenheit Scale1

Kelvin scale

  1. Termed after William Lord Kelvin. It is SI unit of measuring temperature and written as K also known as absolute scale as it starts from absolute zero temperature (temperature at which all thermodynamic movements ceases). It is defined as 1/273.16 Th temperature of triple point of water i.e. 0.01*C or 32.018*F.
  1. K can be easily converted to *C or *F,

K = 273 + *C

Must know temperatures of human body

Condition *C*FK
Normal body temperature 37*C 98.6*F 310 K
Hypothermia (hypo means below and thermo means heat or temperature) Below 35*C Below 95*F 308 K
Medical emergency Below 32*C Below 90*F 305 K
Fever/hyperthermia 38*C 100.4*F 311 K
High fever 39*C 102.2*F 312 K
Life threatening (dehydration, vomiting,nausea, fainting) 40*C 104*F 313 K
Medical emergency 41*C 105.8*F 314 K

Important temperatures in Chemistry

Freezing point of water 0°C 32°F 273K (Exact is 273.15K)
Boiling point of water 100°C 212°F 373.15K
Triple point of water 0.01°C 32.02°F 373.16K
Maximum density of water 3.98°C 39.16°F 277.13K
Absolute zero temperature -273.15°C -459.67°F 0K


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