$A$ Carnot engine operates between two reservoirs of temperatures $900 \; K$ and $300 \; K$. The engine performs $1200 \; J$ of work per cycle. The heat energy (in $J$) delivered by the engine to the low-temperature reservoir in a cycle is:

An ideal gas heat engine operates in a Carnot cycle between $227^{\circ}C$ and $127^{\circ}C$. It absorbs $6 \times 10^4 \, J$ of heat at the high temperature. The amount of heat converted into work is:

The efficiency of a Carnot engine is $50\%$ and the temperature of the sink is $500 \ K$. If the temperature of the source is kept constant and its efficiency is raised to $60\%$,then the required temperature of the sink will be: (in $K$)

The temperature of food material in a refrigerator is $4^{\circ} C$ and the temperature of the environment is $15^{\circ} C$. If a Carnot cycle is used in its working gas,find its Carnot efficiency.

Two Carnot engines $A$ and $B$ operate in series such that engine $A$ absorbs heat $Q_1$ at temperature $T_1$ and rejects heat $Q$ to a sink at temperature $T$. Engine $B$ absorbs half of the heat rejected by engine $A$ (i.e.,$Q/2$) and rejects heat $Q_3$ to the sink at temperature $T_3$. When the work done in both cases is equal,the value of $T$ is:

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 ${\eta _1}/{\eta _2}$?