What is calorimeter ? What is Calorimeter ? Explain its principle and construction.

Explanation

Calorimetry means measurement of heat.
A device in which heat measurement can be made is called calorimeter.
When there is no heat exchange between system and surroundings, then it is called isolated system.
When different parts of an isolated system are at different temperature, a quantity of heat transfers from the part at higher temperature to the part at lower temperature. The heat lost by the part at higher temperature is equal to the heat gained by the part at lower temperature.
When a body at higher temperature is brought in contact with another body at lower temperature, the heat lost by the hot body is equal to the heat gained by the colder body, provided no heat is allowed to escape to the surroundings.
Construction :
It consists a metallic vessel and stirrer of the same material like copper or aluminium.
The vessel is kept inside a wooden jacket which contains heat insulating materials like glass, wool etc.
The outer jacket acts as a heat shield and reduces the heat loss from the inner vessel.
There is an opening in the out jacket through which a mercury thermometer can be inserted into the calorimeter.