Question

A refrigerator whose coefficient of performance is 5 extracts heat from the cooling compartment at the rate of 250 j/cycle. How much electric energy is spent per cycle?How much heat per cycle is discharged to the room?

Answer 1

Q2= 250J/CYCLE

COP=5

COP=Q2/W

W=Q2/COP

W=250/5=50

HEAT DISCHARGED /CYCLE TO THE ROOM

Q1=Q+W=250+50=300J/CYCLE

Answer 2

Answer: The electric energy spent per cycle is 50 J.

              The heat discharged per cycle is 300 J.

Explanation:

The expression for the coefficient of performance is as follows;

$K=\frac{Q_{2}}{W}$

Here, K is the coefficient of performance, W is the work done and ${Q_{2}}$ is the heat removed.

Calculate the electric energy spent per cycle.

Put K= 5 and ${Q_{2}= 250 J$.

$5=\frac{ 250}}{W}$

W= 50 J

Therefore, the electric energy spent per cycle is 50 J.

Calculate the heat discharged per cycle.

$Q_{1}=Q_{2}+W$

Here, $Q_{1}$ is the heat absorbed.

Put  ${Q_{2}= 250 J$ and W= 50 J.

$Q_{1}=250+50$

$Q_{1}=300 J$

Therefore, the heat discharged per cycle is 300 J.