Heat Pumps

Q.

What is the relation between the efficiency $\mathrm{\eta }$ of a heat engine and the co-efficient of performance $\mathrm{\alpha }$ of a refrigerator?

Q. Considering an ideal refrigerator, heat from its inside at a temperature of $277\text{K}$ is transferred to a room at temperature of $300\text{K}$. Find the amount of heat extracted for each Joule of electrical energy consumed by refrigerator.

1. $1\text{J}$
2. $1.3\text{J}$
3. $12\text{J}$
4. $15\text{J}$

Q. The temperature inside a refrigerator is $t_2^{}°C$ and the room temperature is $t_1^{}°C$. The amount of heat delivered to the room for each joule of electrical energy consumed ideally will be

1. $\frac{t_2+273}{t_1-t_2}$
2. $\frac{t_1+t_2}{t_1+273}$
3. $\frac{t_1}{t_1-t_2}$
4. $\frac{t_1+273}{t_1-t_2}$

Q. An ideal refrigerator has a freezer at a temperature of $-{13}^{\circ }\text{C}$. The coefficient of performance of the engine used is $5$. The temperature of the air (to which heat is rejected) will be

1. ${325}^{\circ }\text{C}$
2. $325\text{K}$
3. ${39}^{\circ }\text{C}$
4. ${320}^{\circ }\text{C}$

Q. Which of the following diagram correctly represents the working of a Carnot's refrigerator?

1. 
2. 
3. 
4.