Thermodynamics Concept – Refrigerator in a Sealed, Insulated Room
Question:
A brand new, empty, electrically powered refrigerator with its doors removed is placed in a sealed, perfectly insulated room and is plugged in and turned on remotely.
After some time, what happens to the average temperature of the air in the room?
- A. Decreased
- B. Stayed exactly the same
- C. None of these answers
- D. Increased ✅
Answer and Explanation:
Step 1: Understanding the Working of a Refrigerator
A refrigerator functions as a heat pump. It absorbs heat from the internal compartment and releases it into the external environment. To do this, it consumes electrical energy.
Step 2: What Happens in a Sealed, Perfectly Insulated Room?
- The room is sealed, so no heat escapes.
- The room is perfectly insulated, so no energy can enter or leave the system.
- Thus, all energy transformations occur within the room.
Step 3: Effect of Removed Doors
With the doors removed, the refrigerator has no separate internal compartment. It is now just circulating air and transferring heat within the same room.
Step 4: Energy Flow and Heat Generation
- Electrical energy is consumed by the refrigerator motor.
- That energy is ultimately converted into heat within the room.
- In addition, the refrigerator transfers heat from one part of the room (evaporator side) to another part (condenser side).
- But the total heat inside the room increases because of the electrical input.