The second law of thermodynamics says that when energy from one form to another form, or the matter moves freely, entropy (disorder) in a closed system increases. Entropy is a measure of spread of matter and energy to every where they have access. This course will include the discussion on heat engine, refrigerator and heat pump. Carnot cycle in forward and reverse direction will also be discussed. Moreover, we will also tend to cover all the GATE questions related to the above mentioned topics.