Heat Engines and Refrigerators

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

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

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 

Assertion For given source and sink temperatures efficiency of Carnot's engine is $100\%$.

Reason For given source and sink temperatures efficiency of Carnot's engine is maximum.

A system undergoes a cyclic process in which it absorbs $Q_1$ heat and gives out $Q_2$ heat. The efficiency of the process is $\eta$ and work done is $W$. Select the correct statement.

Efficiency of carnot engine is (input temperature $=T_1$, exhaust temperature $=T_2$)

A Carnot's heat engine working between the temperature limits $400 \mathrm{K}$ and $800 \mathrm{K}$ has a work input of $1000 \mathrm{J}$ per cycle. The heat energy supplied by the source to the engine per cycle is:

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.

Two Carnot's engines $A$ and $B$ have the same efficiency. $A$ receives heat from a source at $800 \mathrm{K}$ and rejects to a sink at  $\text{'}x\text{'}$ kelvin. $B$ receives heat rejected by $A$ and rejects to another sink at $300 \mathrm{K}$. The temperature  $\text{'}x\text{'}$ is nearly _____.