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Nilanjan Bhowmick AIR 3, CSIR NET (Earth Science)
- IIT JAM
- Physics (PH)
Thermodynamics2
i am asking this once again that why option B is correct although T1/T2 is not equal to Q1/Q2
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Abhishek singh
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Why Carnot engine is special one? What makes it different from other heat engine? These are some doubts, you must have! Carnot engine is an ideal case, which is not practically possible. The reason is, we assume Carnot engine to be reversible, but no process in this universe is reversible! For any heat engine, you can use efficiency (n) = 1 - Q2/Q1. But you have a special form for efficiency for the case of reversible engine (i.e. Carnot engine) and the formula gets reduced to, n = 1- Q2/Q1 = 1- T2/T1. you can only use the temperature form for reversible ( or ideal or Carnot) engine. Now it's home work time for you. Check efficiency by both formulas in all four option. If efficiency by Temperature formula comes out to be greater than efficiency by Heat formula (i.e efficiency of reversible engine is greater than efficiency of normal heat engine, then it's possible, that respective option is acceptable as answer (i.e. option A and B)). Best regards.
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Shanu arora Best Answer
because heat engine is a different thing and carnot heat engine is a different thing . as explained before , carnot is just an ideal condition (Q1/Q2 = T1/T2) ------eqn(1), which comes from carnot cycle but engine are different as well , for any general engine where it is not mentioned that it is carnot engine ,one cannot use eqn (1) . so I think it's now clear that that every heat engine is not carnot engine ,but every carnot engine is a heat engine . please find attached Carnot's theorem which I have used for this question to find which engines can be possible heat engines.
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Ruby negi![best-answer]()
A theorem known as Carnot theorem states that no heat engine have efficiency higher than or equal to Carnot engine working between same two temperature. in this case , when we find efficiency using temperature it is .5 ,then using heat this is different in all options, in option b it is less than 0.5 so it is a practical heat engine because ol other engine have efficiency greater than 0.5.. Carnot engine is the most efficient engine....
Heat engine is which has efficiency less than the Carnot engine working between the same temperature.. so in the case 0.5is the efficiency of Carnot engine means heat engine must have a efficiency less than 0.5.. so we have a heat engine which receive 100 j heat and reject 75j heat.. option b
this case**