The negative sign indicates that heat is transferred in the direction of decreasing temperature. The heat flow will be in the perpendicular-to-the-cross-section direction, i.e. one-dimensional.
To determine how much heat is provided, we will calculate how much heat is taken (absorb) by the cold water at steady state condition. (it is the condition at which heat supplied is equal to the heat removed). For this we use the relation
Where Q is the rate of heat transfer, s is specific heat capacity of water , Tout is the temperature of water at outlet and Tin is the temperature of water at inlet. Putting the value of Q in (ii), we get
The apparatus consist of accessories for providing heat at one end of sample composite bar and for taking heat at the other end of the bar through water. The water inlet temperature and outlet temperature was measured through thermometers. To determine the volume of water the measuring flask was provided. To determine the temperature at different points along the bar thermocouples were provided. The whole apparatus was well insulated to ensure one dimensional heat flow.
The heater was switched on and as the circulation of water through the cavity. Readings at thermocouples 1,2,3 and 4 were taken when the steady state condition was achieved. The volume of water circulating was measured and time taken for this. The inlet and outlet temperature of water is also measured.
Heat transfer has taken place because of the difference of temperature between two ends of sample bar (consisting of copper and stainless steel). From graph slopes of copper and stainless steel shows that drop in temperature per unit length in copper bar is less as compared to stainless steel, which indicates that copper has let more heat to be transferred through it. Similar result is given by the calculated thermal conductivities showing that copper thermal conductivity is greater as compare to stainless steel.