Which of the following statement is not true about heat engine?
Correct answer: C. Efficiency of Carnot engine working between same two temperatures, depends on the nature of working substance
- A. All real engines are less efficient than Carnot engine
- B. All real engines are less efficient due to friction and heat losses
- C. Efficiency of Carnot engine working between same two temperatures, depends on the nature of working substance
- D. The larger the temperature difference of two reservoirs, the greater is the efficiency.
Explanation
Option C is correct since it's the only incorrect statement as the efficiency of a 'Carnot engine' depends solely on the temperatures of the hot and cold reservoirs.The efficiency of a Carnot engine, which is the theoretical maximum efficiency for a heat engine operating between two temperature reservoirs, depends only on the temperatures of the reservoirs and is independent of the nature of the working substance. This efficiency is the maximum achievable efficiency for any heat engine operating between the same two temperature reservoirs. The Carnot efficiency is a function of the temperatures only and is not influenced by the specific properties of the working substance. The proof of this result is based on the second law of thermodynamics and relies on the assumption that the Carnot engine is reversible and operates in a cycle.In practice, no real engine can reach the Carnot efficiency because of irreversibilities and losses in actual processes. However, the Carnot efficiency serves as a benchmark for the maximum efficiency that any heat engine can achieve.
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About First Law of Thermodynamics
The first law relates heat supplied, work done and the change in internal energy through energy conservation. Problems use sign conventions and apply the law to isothermal, adiabatic, isobaric and isochoric processes. Internal energy is a state function, while heat and work depend on the path followed.
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