In a mechanical refrigerator, the low temperature coils are at a temperature of $-23^{\circ}C$ and the compressed gas in the condenser has a temperature of $27^{\circ}C$. The theoretical coefficient of performance is

What is an ideal refrigerator?

The coefficient of performance of a refrigerator is defined as:

In a refrigerator,one removes heat from a lower temperature and deposits it to the surroundings at a higher temperature. In this process,mechanical work has to be done,which is provided by an electric motor. If the motor is of $1\,kW$ power and heat is transferred from $-3\,^{\circ}C$ to $27\,^{\circ}C$,find the heat taken out of the refrigerator per second,assuming its efficiency is $50\%$ of a perfect engine.

An ideal heat engine has an efficiency $\eta$. The coefficient of performance of the engine when driven backward will be

The temperature inside a refrigerator is $t_2 \, ^\circ C$ and the room temperature is $t_1 \, ^\circ C$. The amount of heat delivered to the room for each joule of electrical energy consumed ideally will be: