The degree of hotness or coldness of a body is known as its temperature.
Temperature of a system depends upon the kinetic energy of its molecules. Higher is the kinetic energy of molecules, higher is its temperature and vice versa.
The measurement of temperature with the help of some instrument is known as thermometry and the instrument which is used to measure the temperature is known as thermometer.
Temperature scale: There are two scales used to measure the temperature of a system.
- Centigrade & Fahrenheit scale
- Kelvin scale
Centigrade (°C) & Fahrenheit (°F) scale: In centigrade scale, two limits of 0°C (ice point) and 100°C (steam point) are fixed as lower and upper limits.
In Fahrenheit scale, two limits of 32°F (ice point) and 212°F (steam point) are fixed as lower and upper limits.
Ice point is the temperature of a mixture of water and ice at pressure of one atmospheric (100kN/m2).
Steam point is the temperature of a mixture of water and steam at pressure of one atmospheric (100kN/m2).
Kelvin scale (°K): It is the absolute scale related to centigrade scale.
°K = °C + 273.15