heat sometimes the temperature of the body will increase or sometimes it may not increase. There is a misconception that heat is a quantity of energy. People often talk ‘this water has more heat or less heat’. These words are meaningless.
Heat is not a quantity. Heat is an energy in transit which flows from higher temperature object to lower temperature object. Once the heating process is stopped we cannot use the word heat. When we use the word ‘heat’, it is the energy in transit but not energy stored in the body.
Note EXAMPLE . a. ‘A lake has more rain’. b.
‘A hot cup of coffee has more heat’. What is wrong in these two statements? Solution a. When it rains, lake receives water from the cloud.
Once the rain stops, the lake will have more water than before raining. Here ‘raining’ is a process which brings water from the cloud. Rain is not a quantity rather it is water in transit. So the statement ‘lake has more rain’ is wrong, instead the ‘lake has more water’ will be appropriate.
Figure . Difference between work and heat A person rubbing his hands Keeping the hands on chin - - - - Unit Heat and thermodynamics . THERMAL PROPERTIES OF MATTER . .
Boyle’s law, Charles’ law and ideal gas law For a given gas at low pressure (density) kept in a container of volume V, experiments revealed the following information. When the gas is kept at constant temperature, the pressure of the gas is inversely proportional to the volume. µ . It was discovered by Robert Boyle ( - ) and is known as Boyle’s law.
When the gas is kept at constant pressure, the volume of the gas is directly proportional to absolute temperature. µ . It was discovered by Jacques Charles ( - ) and is known as Charles’ law. By combining these two equations we have PV = CT.
Here C is a positive constant. We can infer that C is proportional to the number of particles in the gas