Question

Sadi Carnot came up with a hypothetical heat engine that had the maximum possible efficiency. What discovery did Carnot make that helped him recognize how to create this "perfect" heat engine?

Answer 1

The discovery which Carnot made was that THE DIFFERENCE IN THE TEMPERATURES BETWEEN THE HOT AND THE COLD RESERVOIRS DETERMINE HOW WELL A HEAT ENGINE WOULD WORK.
Sadi Carnot was a French engineer, He proposed a theoretical thermodynamic cycle in 1824. In his cycle, Said hold that the efficiency of a heat engine depends on the temperature difference between its hot reservoir and cold reservoir.