Heat Engines and Refrigerators

An ideal Carnot engine working with source temperature $T_1$ and sink temperature $T_2$, has efficiency $\eta$. Then the value of the ratio $\frac{T_1}{T_2}$ is

A diatomic ideal gas is used in a carnot engine as the working substance. If during the adiabatic expansion part of the cycle, the volume of the gas increases from $V$ to $32 \mathrm{V}$, the efficiency of the engine is,

Even Carnot engine cannot give $100\%$ efficiency because we cannot

A Carnot engine works between constant temperature $T_1$ and $T_2$ of source and sink, respectively. For efficiency to be greatest

The efficiency of all reversible heat engines operating between the same heat reservoirs is :

A Carnot engine whose low-temperature reservoir is at $350 \mathrm{K}$ has an efficiency of $50\%$ . It is desired to increase this to $60\%$ . If the temperature of the low-temperature reservoir remains constant, then the temperature of the high-temperature reservoir must be increased by how many degrees?

Consider a reversible engine of efficiency $\frac{1}{6}$ . When the temperature of the sink is reduced by $62{ }^{\mathrm{o}}\mathrm{C}$ , its efficiency gets doubled. The temperature of the source and sink respectively are

When temperture ${\mathrm{T}}_1$ of heat reservoir increases by ${200}^{\mathrm{o}}\mathrm{C}$, the efficiency of the engine is nearly equal to __, if the temperatures $T_1$ and $T_2$ of heat reservoirs in an ideal Carnot engine are ${1800}^{\mathrm{o}}\mathrm{C}$ and ${600}^{\mathrm{o}}\mathrm{C}$ respectively. 

A refrigerator is to maintain the eatables, kept inside it, at $9°\mathrm{C}$. The coefficient of performance of the refrigerator, if the room temperature is $36°\mathrm{C}$, is

The efficiency of the Carnot engine is $50\%$ and the temperature of the sink is $500 \mathrm{K}$. If temperature of the source is kept constant and its efficiency is raised to $60\%$, then the required temperature of the sink will be

The efficiency of the Carnot engine is $50\%$ and the temperature of the sink is $500 \mathrm{K}$. If the temperature of the source is kept constant and its efficiency raise to $60\%$, then the required temperature of the sink will be

A reversible heat engine converts one- fourth of the heat input into work. When the temperature of the sink is reduced by $52 \mathrm{K},$ its efficiency is doubled. The temperature in Kelvin of the source will be __________ .

An engine operates by taking a monoatomic ideal gas through the cycle shown in the figure. The percentage efficiency of the engine is close to _____.

An ideal heat engine exhausting heat at $77°\mathrm{C}$ is to have a $30\%$ efficiency. It must take the heat at:

An ideal refrigerator has a freezer at a temperature of $-13°\mathrm{C}$. The coefficient of performance of the refrigerator is $5.$ The temperature of the air (to which heat is rejected) will be:

The temperatures $T_1$ and $T_2$ of heat reservoirs in the ideal Carnot engine are $1227 °\mathrm{C}$ and $527 °\mathrm{C}$ respectively. If $T_1$ increases by $100 °\mathrm{C}$, the efficiency of the engine in percentage is

A Carnot engine absorbs $750 \mathrm{J}$ of heat energy from a reservoir at $137 \mathrm{℃}$ and rejects $500 \mathrm{J}$ of heat during each cycle, then the temperature of sink is

An ideal gas heat engine operates in a carnot cycle between $227°\mathrm{C}$ and $127°\mathrm{C}$. It absorbs $6 \mathrm{kcal}$ at the higher temperature. The amount of heat (in $\mathrm{kcal}$) converted into work is equal to 

A carnot refrigeration cycle absorbs heat at $270 \mathrm{K}$ and rejects heat at $300 \mathrm{K}.$ If the cycle is absorbing $1260 \mathrm{kJ}/\min$ at $270 \mathrm{K},$ then work required per second is:

A heat engine is operating between $500 \mathrm{K}$ to $300 \mathrm{K}$. If the engine absorbs $100 \mathrm{J}$ heat, then which of the following is impossible amount of heat rejected by this heat engine.