An electric room-heater is placed near the floor of a closed room in winter
PHYSICS · Subjective · CBSE · Physics · Thermal Properties of Matter · Thermal Properties of Matter
Problem
An electric room-heater is placed near the floor of a closed room in winter. After some time a ceiling fan is switched on and run at low speed while the heater continues to operate.
(a) Identify the principal mode by which the heater initially warms the air in its immediate neighbourhood and explain the physical reason for this choice.
(b) Describe qualitatively how the motion of air produced by the ceiling fan redistributes the heat within the room. State the mode of heat transfer chiefly responsible for this redistribution.
(c) Compare, with reasons, the overall effectiveness of room heating with the fan switched ON and with the fan kept OFF.