The door of an operating refrigerator is kept open. As a result,the temperature of the room will

$A$ 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

The efficiency of a reversible heat engine working between two temperatures is $50 \%$. The coefficient of performance of a refrigerator working between the same two temperatures but in reverse direction is

An electrical refrigerator with $\beta=5$ extracts $5000 \,J$ from the contents of the refrigerator. During this process, find the electrical energy utilised by its motor. (in $\,kJ$)

$A$ Carnot engine having an efficiency of $1/5$ as a heat engine is used as a refrigerator. If the work done on the system is $50 \ J$,then the amount of energy absorbed from the reservoir at the lower temperature is (in $J$)

Define and write the formula for the coefficient of performance of a refrigerator.