Question

explain how all the air in a room gets heated when a room heater kept on the floor in a corner of the room is switched on

Answer 1

the heat is transferred through 3 ways
conduction-in solid
convection- liquid and gas
Radiation - in spaces
so in room there is air .
The air which comes in contact with the heater's coil heat heated and goes up and other cold air from the room replaces it's position and comes in contact with the heater's coil then heated up and goes up this process is repeated which is convection process.
Thus all the air of room gets hot.

Answer 2

Explanation:When we close the room and open the gate of fridge so the room will quickly get cooled , so in the same way when heater  is on the heat rises in the cool air because it is less dense . as the there are three ways of passing the heat :

convection , conduction , radiation . so a convection heater blow warm air,and air is lighter so the room get heated immediately.