The coefficient of performance of a Carnot refrigerator working between temperatures $30 \, ^\circ\text{C}$ and $0 \, ^\circ\text{C}$ is:

Write the formula for the coefficient of performance of a heat pump.

$A$ Carnot's engine works as a refrigerator between $250\, K$ and $300\, K$. It receives $500\, cal$ heat from the reservoir at the lower temperature. The amount of work done in each cycle to operate the refrigerator is ..... $J$

The temperatures inside and outside a refrigerator are $273 \, K$ and $300 \, K$ respectively. Assuming that the refrigerator cycle is reversible,for every joule of work done,the heat delivered to the surrounding will be nearly ........ $J$.

$A$ refrigerator with a coefficient of performance $0.25$ releases $250 \, J$ of heat to a hot reservoir. The work done on the working substance is

$A$ Carnot engine having an efficiency of $\frac{1}{10}$ is being used as a refrigerator. If the work done on the refrigerator is $10 \; J,$ the amount of heat absorbed from the reservoir at lower temperature is .............. $J$.