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Himanshu posted an Question
April 25, 2020 • 08:30 am 30 points
  • IIT JAM
  • Physics (PH)

Heat engine

solve?? .

2 Answer(s) Answer Now
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  • 4 Comments
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  • Himanshu Pandey

    But for option B Q1/Q2 is not equal to T1/T2 like option so why it also correct. MOREOVER how this solution is proceeding??

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    Ruby negi

    Heat  engine takes energy from a hot reservoir(having high temperature) and uses part of it to do work,& exhaust a part of the energy to a cold reservoir(having low temperature). So Q1 is the heat received by engine from the source at high temperature T1 and Q2 it he amount of heat rejected by the engine to the sink at low temperature T2..the efficiency of engine in terms of temperature is 1-(T2/T1) and in terms of heat exchange is 1-(Q2/Q1).. efficiency must be less than 1 as no engine can be 100%efficient.. here in this ques, temperature is constant in all options means u have a engine which receive heat from source at temp 1000k and reject heat to sink at temp 500k, by using these u can find efficiency and that is 0.5 so this is a practical heat engine.. using efficiency in terms of heat ,u can find the heat reject to sink( as heat receive is same in all options). therefore option a is correct.. best regards.

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    Shanu arora Best Answer

    Option A and B are correct answer .A machine operating between two temperatures can only be an engine if it's efficiency is less than the carnot engine working between the same two temperatures i.e carnot engines have max efficiency and No heat engine can be more efficient. The same condition goes for refrigerators , pump ,etc . Here is the detailed solution ,free feel to ask doubts .

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    Abhishek singh best-answer

    Remember, for reversible heat engine, we have two fromulas for calculating efficiency, one in terms of heat exchange and other in terms of temperatures of sink and source. if efficiency by both the formulates comes out to be same, then this engine is called heat engine. I have checked for option A, and it comes out to be true. after having the result(q2/q1 = T2/T1) in mind, you can directly tick the correct option, just by looking at the options. Best regards.

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