The efficiency of a Carnot engine which operates between the two temperatures $T_1 = 500 \text{ K}$ (source) and $T_2 = 300 \text{ K}$ (sink) is: (in $\%$)

The efficiency of a Carnot heat engine is $25 \%$ and the temperature of its source is $127^{\circ} C$. Without changing the temperature of the source,if the absolute temperature of the sink is decreased by $10 \%$,the new efficiency of the engine is: (in $\%$)

The efficiency of a Carnot engine depends on what,and of what is it independent?

$A$ Carnot cycle consists of

In a Carnot engine,when ${T_2} = {0^o}C$ and ${T_1} = {200^o}C$,its efficiency is ${\eta _1}$. When ${T_1} = {0^o}C$ and ${T_2} = -{200^o}C$,its efficiency is ${\eta _2}$. What is the ratio ${\eta _1}/{\eta _2}$?

In practice,all heat engines have an efficiency less than that of a Carnot engine because