Q5

 

Fridge in Room

There is a room perfectly heat sealed so that transfer of heat from room to outside or from outside to room is not possible. Temperature sensor is provided in the room to monitor room temperature from outside. One fridge is also in the room.

 As experiment, the room is closed after switching ON fridge with its door open.

 Room temperature is observed after about ten hours running of fridge with its door open in this closed room.

 There are three probabilities.

Either room temperature will INCREASE or DECREASE or NO CHANGE.

 What is expected and Why?

Answer

Readers,
Quiz is a mental exercise to enhance reasoning power in the subject. Hence personal attempt for reply is expected before jumping to answer. Answer given here is just for confirmation.

Proceed

There is no scope for the heat to enter or leave the room as room is closed and sealed.

One assumption may be cooled air from the fridge will flow out as its door is open. This will mix with the air in the room. So room temperature will decrease. But this is not correct.

 Fridge is a heat transfer device. It absorbs heat from inside of the fridge and released outside into surrounding. Because one way fridge transferring heat from inside to out in the room. But cold air from the fridge is mixing with the air in the room as its door is open. Hence total heat content of the room remains the same. So other assumption may be no change in room temperature. But this is also not correct.

Second assumption is partially right. But the fridge consumes electricity for its operation. Heat is produced by this energy is additional. Therefore total heat content in the room increases. So room temperature will increase.