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Physics GK · Q23

Heat and Thermodynamics

Competitive Exams · Physics GK · question 23

Q23

In a refrigerator, what produce the cooling?

A.
The ice which deposits of the freezer
B.
The sudden expansion of compressed gas
Answer
C.
The evaporation of a volatile liquid
D.
None of the above

Answer: Option B

Solution

Answer: Option B
Solution:
Refrigerators work by using a special substance that changes easily between liquid and gas.

Option A is incorrect because the ice in the freezer is a *result* of the cooling, not the *cause*.

Option B is the correct answer. The refrigerator uses a compressor to squeeze a gas, making it very hot. This hot gas then passes through coils (usually on the back of the fridge) where it releases its heat into the surrounding air. After that, the gas expands suddenly, and this expansion makes it much colder. This cold gas then absorbs heat from the inside of the refrigerator, cooling it down.

Option C is partially correct. While the *evaporation* of a liquid does cool things down, in a refrigerator, the cooling is mainly due to the sudden expansion of the compressed gas. The evaporation plays a supporting role in the cycle.

Option D is incorrect because the correct answer is Option B.