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Thermodynamics — Physics STD 11 Science — Question

Gujarat BoardEnglish MediumSTD 11 SciencePhysicsThermodynamics2 Marks
Question
Explain, what do you understand by the efficiency of a heat engine?
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Answer

The efficiency of a heat engine is stated as the ratio of the net work done by the heat engine and heat absorbed by the working substance. Suppose a heat engine absorbs $Q_1$ heat from the hot reservoir and gives $Q_2​​​​​​​$ heat rejected to the colder reservoir. So, the work done by the working substance is, $W = Q_1 - Q_2​​​​​​​$ So effieciency of heat engine, $\eta=\frac{\text{W}}{\text{Q}_1}=\frac{\text{Q}_1-\text{Q}_2}{\text{Q}_1}=1-\frac{\text{Q}_2}{\text{Q}_2}$

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