# What is the Law of Heat Exchange in Physics

## Law of Heat Exchange in Physics

For an isolated system comprising mixture of hot and cold substances, the heat lost by hot substances is equal to the heat gained by cold substances.

Heat lost by hot body = Heat gained by cold body

Refrigerator:

Introduction:

A refrigerator is a device that is used to keep fruits, vegetables and other eatables cool.

Construction:

A refrigerator consists of a compressor, condenser and evaporator.

Refrigerant:

Freon is used as the refrigerant in a refrigerator. This gas liquefies at normal temperature if the pressure is increased.

Working:

1. Compression: Freon gas is first compressed in the compressor of a refrigerator. It is then fed into the condenser.

1. Condensation: In the condenser, the gas is liquefied under pressure. It converts into a liquid at normal temperature. This gas is then allowed to pass through a valve into the evaporator.

1. Evaporation: The pressure in the evaporator is comparatively less than in the condenser. Therefore, when liquid Freon enters the evaporator, it evaporates absorbing a large amount of heat. This results in cooling the area around the evaporator. This is where we keep our eatables.
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