# A real engine has an efficiency of 33%. The engine has a work output of 24 j per cycle (a) How much hear energy is extracted from the high temperature reservoir per cycle      (A) 8 J                  (B) 16 J               (C) 48 J                               (D)72 J                                                         (E) the question can be answered only if theengine is a carnot engine.     (b) How much heat energy is discharged into the low temperature reservoir per cycle?                                                           (A) 8 J  (B) 16 J               (C) 48 J               (D) 72 J               (E) the question can be answered only if the engine is a carnot engine.(c) For this engine TL = 27ºC. What can be concluded about TH? (A) TH   = 450ºC              (B)TH=177ºC.                                                                                                              (C) TH > 177ºC.               (D)TH(E) 177ºC H

9 years ago
(a) The correct option is (D) 72 J.
The efficiency ε of a Carnot engine is defined as,

Urjita Sharma
21 Points
7 years ago
As the formula of efficiency is only applicable to Carnot engines and as this is a real engine the first two questions cannot be answered. Thus option E for both.If it were a Carnot`s engine, then TH would have been 177°C . Considering a Carnot`s engine having The as 177 C would give efficiency of 33% but as this is a real engine its efficiency must be less than 33%. Hence if it is 33% then it`s TH must be greater than 177°C.
Urjita Sharma
21 Points
7 years ago
The answer for first two can be given by the formula e= W/Qh1/3= 24/QhQh=72J1/3=1-Ql/QhQl= 48JPardon my previous answer was wrong.The third part is pretty much fine.
Urjita Sharma
21 Points
7 years ago
For the third part, if the efficiency is less than a Carnot`s engine, for a Carnot`s engine its The would be 177C e=W/Qh Qh proportional to Th hence e is inversely proportional to Th thus as e is less than will be more than 177C