The efficiency of a Carnot engine when the source temperature is $T_1$ and the sink temperature is $T_2$ is given by:

$A$ Carnot engine operating between temperatures $T_1$ and $T_2$ has an efficiency of $0.2$. When $T_2$ is lowered by $45 \text{ K}$, its efficiency becomes $0.5$. The temperatures $T_1$ and $T_2$ are respectively:

$A$ Carnot engine with sink's temperature at $17\,^{\circ}C$ has $50\%$ efficiency. By how much should its source temperature be changed to increase its efficiency to $60\%$? (in $K$)

$A$ scientist claims that the efficiency of their heat engine,which operates between a source temperature of $127^{\circ}C$ and a sink temperature of $27^{\circ}C$,is $26\%$. Then:

$A$ 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 $K$)

What is the source temperature of the Carnot engine required to get $70 \%$ efficiency (in $^{\circ}C$)? Given sink temperature $= 27^{\circ}C$.