Refrigerator / Heat Pump — Practice Quiz

Question 1

A refrigerator extracts 200 J from cold and dumps 250 J to hot. Work input:

Accepted Answer

50 J

Answer

200 J

Answer

450 J

Answer

250 J

Question 2

Carnot refrigerator COP between 250 K and 300 K:

Accepted Answer

5

Answer

1

Answer

10

Answer

50

Question 3

Coefficient of performance of a refrigerator can be:

Accepted Answer

Greater than 1 (typically 2-4)

Answer

Less than 1 only

Answer

Equal to 1 only

Answer

Always exactly 1

Question 4

Heat pump for heating with COP_ref = 3:

Accepted Answer

Heat output = 4W (since heat pump = 1 + COP_ref)

Answer

Heat output = 3W

Answer

Heat output = W

Answer

Heat output = 0

Question 5

Clausius statement of 2nd law:

Accepted Answer

Heat cannot flow from cold to hot without work input

Answer

All engines are 100% efficient

Answer

Heat flows only in one direction

Answer

Energy is conserved