- (a) Describe the mechanism of heat transfer by conduction. [2]
The diagram shows a wall separating the inside of a room from the outside. The temperature of the room is kept constant by a heater.
(b) Estimate the rate at which thermal energy leaves the room through the wall giving the answer with an appropriate unit. [2]
(c) At night the outside temperature falls below 13 °C. The heater is turned off at time t = 0. The graph shows the variation with time t of the temperature T of the room.
(i) Outline why the magnitude of the gradient of the graph decreases. [1]
(ii) The pressure and volume of the air in the room remain constant but the number of molecules has increased. Determine the percentage increase in the number of molecules of air in the room between t = 0 and t = 120 min. [3]
(d) Discuss how the second law of thermodynamics applies to the situation of the room cooling down. [2]