The temperature of the source of a Carnot engine operating with an efficiency of $70\%$ is $1000 \ K$. The temperature of its sink is ...... $K$.

In a Carnot engine,if the temperatures of the source and the sink are decreased by $100 \ K$ each,then the efficiency of the engine:

$A$ car engine has a power of $20 kW$. The car makes a round trip of $1$ hour. If the thermal efficiency of the engine is $40 \%$ and the ambient temperature is $300 K$, the energy generated by fuel combustion is: (in $kJ$)

$A$ Carnot engine operates between a source and a sink. The efficiency of the engine is $40 \%$ and the temperature of the sink is $27^{\circ} C$. If the efficiency is to be increased to $50 \%$,then the temperature of the source must be increased by: (in $K$)

The temperature of the sink of a Carnot engine is $27^\circ C$. The efficiency of the engine is $25\%$. Then the temperature of the source is ...... $^\circ C$.

Explain heat engines and their working.