Which of the following instruments helps to maintain the correct humidity and temperature of a building?

Analysis

The question asks for an instrument designed to regulate both the humidity (the amount of water vapor in the air) and the temperature (the degree of hotness or coldness) within an enclosed space like a building.

Concept Explanation

To understand this, we look at the functions of the options provided:

• Compressor: This is a component inside cooling systems that increases the pressure of a refrigerant. It is not a complete system on its own.
• Refrigerator: This is designed to keep a small, insulated compartment cold to preserve food. It does not regulate the humidity and temperature of an entire building.
• Air blower: This simply moves air from one place to another; it does not change the temperature or humidity of the air.
• Air conditioner: This is a system designed to provide thermal comfort and indoor air quality. It works by drawing in warm air, passing it over cooling coils (which removes heat and condenses excess moisture/humidity), and circulating the cooled, dehumidified air back into the room.

Step-by-Step Solution

1. Temperature Control: An air conditioner uses a refrigeration cycle to remove heat from the indoor air, effectively lowering the temperature.
2. Humidity Control: As the warm, moist indoor air passes over the cold evaporator coils of the air conditioner, the water vapor in the air condenses into liquid water (which is then drained away). This process significantly reduces the humidity level in the room.
3. Conclusion: Because the air conditioner performs both the cooling of the air and the removal of excess moisture, it is the correct device for maintaining a controlled environment in a building.

Identifying the Answer

Comparing the functions, the Air conditioner is the only device listed that is specifically engineered to manage both environmental factors (temperature and humidity) for human comfort in a building.

Exam Tip

When you see questions about "environmental control" in Physics, look for devices that involve a thermodynamic cycle. An air conditioner is essentially a heat pump that moves heat from inside a building to the outside, and the cooling process naturally acts as a dehumidifier.