$A$ Carnot engine, whose efficiency is $40\%$, takes heat from a source maintained at temperature $600\text{ K}$. To have an efficiency of $60\%$, the intake temperature for the same exhaust temperature should be: (in $\text{ K}$)

Write two essential characteristics of an ideal heat engine.

What is a Carnot engine?

The efficiency of a Carnot engine,working between the steam point and the ice point,will be $....\,\%$ (in $.81$)

$A$ Carnot engine of efficiency $40 \%$ takes heat from a source maintained at a temperature of $500 \ K$. It is desired to have an engine of efficiency $60 \%$. Then,the source temperature for the same sink temperature must be (in $K$)

Two ideal Carnot engines operate in cascade (all heat given up by one engine is used by the other engine to produce work) between temperatures $T_{1}$ and $T_{2}$. The temperature of the hot reservoir of the first engine is $T_{1}$ and the temperature of the cold reservoir of the second engine is $T_{2}$. $T$ is the temperature of the sink of the first engine,which is also the source for the second engine. How is $T$ related to $T_{1}$ and $T_{2}$,if both engines perform equal amounts of work?