Assume that a heat engine attains 100% efficiency. This assumption is made possible only if the output temperature is
Correct answer: A. equal to 0 K.
- A. equal to 0 K.
- B. less than 0 K.
- C. equal to its input temperature.
- D. less than its input temperature.
Explanation
To achieve 100% efficiency, a heat engine would require its output temperature (cold reservoir temperature) to be at absolute zero (0 K). This is based on the Carnot efficiency formula, which states:η = 1 - (T_c / T_h)Where: * η is the efficiency of the heat engine. * T_c is the temperature of the cold reservoir (output temperature) in Kelvin. * T_h is the temperature of the hot reservoir (input temperature) in Kelvin.For the efficiency (η) to be 1 (or 100%), the ratio (T_c / T_h) must be 0. Since T_h (input temperature) is always a positive value (as it's a hot reservoir), T_c (output temperature) must be 0 K.Correct Answer:
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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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