The assumptions made for describing the working of the Carnot engine are as follows :
(i) The piston moving in a cylinder does not develop any friction during motion.
(ii) The walls of piston and cylinder are considered as perfect insulators of heat.
(iii) The cylinder head is so arranged that it can be a perfect heat conductor or perfect heat
(iv) The transfer of heat does not affect the temperature of source or sink.
(v) Working medium is a perfect gas and has constant specific heat.
(vi) Compression and expansion are reversible.