A heat engine operates between a hot reservoir at TH=500K and a cold reservoir at TC=300K. During each cycle it absorbs QH=2000J of heat from the hot reservoir.
Answer the following questions.
(i) Using thermodynamic reasoning, determine the maximum possible efficiency that any engine working between these two temperatures can achieve.
(ii) Hence calculate the minimum amount of heat QC that must be rejected to the cold reservoir in each cycle so that the engine does not violate the second law.
(iii) If an actual engine working between these reservoirs rejects only 200J of heat, state with justification whether this engine is permissible under the second law.