The coefficient of performance of a refrigerator is defined as:

The door of a working refrigerator is left open in a well-insulated room. The temperature of the air in the room will

$A$ Carnot engine,having an efficiency of $\eta = 1/10$ as a heat engine,is used as a refrigerator. If the work done on the system is $10 \ J$,the amount of energy absorbed from the reservoir at a lower temperature is ....... $J$.

$A$ household refrigerator with a coefficient of performance $1.2$ removes heat from the refrigerated space at the rate of $60 \ kJ/min$. What would be the cost of running this fridge for one month $(30 \ days)$, assuming it is used for $4 \ hours$ each day and the cost of one electrical unit is $6 \ Rs.$?

$A$ refrigerator consumes an average $35 \ W$ power to operate between temperatures $-10^{\circ}C$ and $25^{\circ}C$. If there is no loss of energy,how much average heat per second does it transfer? (in $J/s$)

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