It is advisable to place room heater at the ground level for effective heating
Answers
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ANSWER :
Its advisable to place room heaters at the ground level for effective heating because as we know warm air being lighter than cold air rises up in the room and displaces the cold air. Consequently the cold air comes down the room, gets heated and again rises up.
Thus, a circulation of hot and cold air up and down the room is created facilitating even and effective heating of the room.
EXPLANATION :
Why warm air is lighter than cold air ? --> This is because when air is heated, the molecules in it expand and their inter molecular spaces increase, i.e they become less dense. Now, less dense air(warm air) floats on more dense air(cold air). An analogy to this is the floating of ice(less dense) on water(more dense).
Hope you find this answer satisfactory and self-explanatory. And if you do, please don't be shy to express your gratitude ;)
PEACE !!