Before knowing the Principle of Pressure cooker first we know the power of the Air. The air have no power when it is in normal state otherwise we compress this it took more power. For example take a injection without needle suck more air. When we compress it the air looks more hard. That shows the real power of the air. Now we want to know the simple Principle that temperature is increase by increasing pressure. Water boils in 100 degree Celsius.
We place the water in the Pressure cooker the increasing the pressure compress the air with high pressure that causes the cooker increase in temperature 141 degree Celsius. This is the major thing to choose the Pressure cooker to cook foods faster. In 1679 French Physicist Denis Papin invented the Cooker for cooking foods more quickly by
compressing air inside the cooker.