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:
Last updated
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.
Practise Thermodynamics
714 free Thermodynamics MCQs from Physics, each with the correct answer and an explanation. Unlimited attempts, no account needed.
Exams that ask Physics questions like this
Physics is on 13 papers prepared for on TestUstad, and all of them draw the same bank, so this question is worth knowing for every one of them.
Related questions
110 J of heat is added to a gaseous system, whose internal energy change is 40 J, then the amount of external work done is
1st law of thermodynamics is consequence of conservation of
A Carnot engine operates between reservoirs at 600 K and 300 K. Its maximum possible efficiency is
A carnot engine working between 200k and 400k has a work output of 600 J per cycle. How much heat energy is supplied to the engine from the source of each cycle.
A chemical system is sealed in a strong rigid container at room temp and then heated vigorously change in work done during the process is: