Question

Let $\eta_1$ is the efficiency of an engine at $T _1=447^{\circ} C$ and $T _2=147^{\circ} C$ while $\eta_2$ is the efficiency at $T _1=947^{\circ} C$ and $T _2=47^{\circ} C$ The ratio $\frac{\eta_1}{\eta_2}$ will be :

• A. $0.41$
• B. $0.56$
• C. $0.73$
• D. $0.70$

Answer 1

Answer: (B)

$0.56$

Answer 2

Efficiency η=1−TH​TL​​
η1​=1−447+273147+273​=1−720420​
η1​=720300​
η2​=1−947+27347+273​=1−1220320​
η2​=1220900​
η2​η1​​=720300​×9001220​=72×3122​
η2​η1​​=0.56