Question

When the temperature difference between the source and the sink increases, the efficiency of the heat engine will

• A. increase
• B. decrease
• C. is not affected
• D. may increase or decrease depending upon the nature of the working substance

Answer 1

The correct option is A increase

The efficiency of the cycle is given as $\eta =1-\frac{T_2}{T_1}$. Here $T_1$ is the temperature of the source and $T_2$ is the temperature of the sink.

If the difference between temperature of the source and the sink is increased (i.e. temperature of source increase or temperature of sink decreases),

the $\frac{T_2}{T_1}$ value decreases and thus efficiency increases.