A sobering thought in this day of energy awareness Suppose y

A sobering thought in this day of energy awareness. Suppose you turn on the furnace to raise the temperature of the air in a room from 19 degree C to 22 degree C. The furnace consumes energy in achieving this increment. Does the energy in the room increase? Why? (Here I am thinking strictly of the energy of the air in the room.) If your answer is no, where has the energy gone? (Recall that, in a realistic house, the pressure in the room remains atmospheric pressure, that is. remains equal to the pressure outdoors.)

Solution

The heat energy consumed by the furnace during temperature rise from 19C to 22C is transffered to the ambience in three ways namely conduction , convection and radiation.

conduction : the furnace will transfer heat to material medium which is in contact with the furnace. if the material medium is in the form of solid (Like walls of the room etc) .

convection: The heat from furnace will transfer to the air in the room by the process of convection.The hot air further will carry heat to the objects in the rooms.

radiation : In this process the furance will loss energy by emitting electromagnetic radiation, Hot objects at a temperautre T will emit energy in the form of radiation energy which is praportion to the T^4 . the radiation energy can escape the room unless sealed for radiation leaks.

the pressure could remains constant since the rise of temperature is from 19C to 22C which is just 3C and not significant to rise the pressure of room, even provided with good air cealing.