The value of efficiency eta for a heat engine | vedclass

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Question

(A) The efficiency $\eta$ of a heat engine is defined as the ratio of the work done $W$ by the engine to the heat $Q_H$ absorbed from the source.$\eta

Vedclass · Accepted Answer

$0$ to $1$

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(A) The efficiency $\eta$ of a heat engine is defined as the ratio of the work done $W$ by the engine to the heat $Q_H$ absorbed from the source.$\eta = \frac{W}{Q_H} = 1 - \frac{Q_L}{Q_H}$According to the second law of thermodynamics,no heat engine can have an efficiency of $1$ $(100\%)$,as it would require the heat rejected to the sink $Q_L$ to be $0$,which is impossible.Also,the efficiency cannot be negative as it would imply the engine is performing work by absorbing heat from a cold reservoir without external work,violating the second law.Therefore,the efficiency $\eta$ always lies between $0$ and $1$ $(0 < \eta < 1)$.

The value of efficiency $\eta$ for a heat engine may lie between

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