The more heat that is converted into work, the more efficient the process. The heat lost to the cold reservoir cannot be recovered. Efficiency is therefore define as the ratio of work out to heat in,…Read More
The Third Law of Thermodynamics says: if two separated systems are in thermal contact with a third, then at equilibrium they all have the same temperature.
Clearly when we bring two blocks together, heat will flow between them. This is an example of coupling systems A to B and to C so eventually the three will be in equilibrium. This coupling only allows heat to flow through direct contact.Read More