$A$ Carnot engine working between $400 \, K$ and $800 \, K$ has a work output of $1200 \, J$ per cycle. What is the amount of heat energy supplied to the engine from the source per cycle in $J$?

Explain why the efficiency of a Carnot engine cannot be $100\%$?

The Carnot cycle is plotted on a $P-V$ graph. Which portion represents an isothermal expansion?

What is the efficiency of a Carnot engine working between the boiling point and the freezing point of water (in $\%$)?

$A$ Carnot engine having efficiency $\frac{1}{6}$ operates between the source temperature $T_H$ and the sink temperature $T_C$. Its efficiency increases to $\frac{1}{3}$ when $T_C$ is decreased by $64 \text{ K}$. The temperatures $T_H$ and $T_C$ are respectively:

$A$ Carnot engine whose low temperature reservoir is at $7\,^{\circ}C$ has an efficiency of $50\%$. It is desired to increase the efficiency to $70\%$. By how many degrees should the temperature of the high temperature reservoir be increased? (in $K$)