1. Heat can be transferred from a high temperature object to a low temperature object via conduction, convection and radiation. a. Explain TWO (2) differences between conduction, convection and radiation. 16 Marks b. Three bars of lead, aluminium and copper are welded together in the series arrangement and perfectly insulated on their sides as shown in FIGURE 1. The free end of lead bar is at 100.0C by the boiling water and the other free end of copper bar is maintained at 0.0C by an ice-water mixture. All bars are of 75 cm long and have a cross section area of 2.5 cm x 2.5 cm. 100C lead aluminium copper 0C FIGURE 1 i. Calculate the temperature at the junctions of lead-aluminium and aluminium-copper bars. 18 Marks ii. Sketch a graph of temperature against bar length from one end of lead bar to the end of copper bar. [2 marks iii. Calculate the rate of heat flow from the boiling water to the ice-water mixture if lead, aluminium and copper bars are welded together in the parallel arrangement as shown in FIGURE 2 below? lead 100C aluminium 0C copper FIGURE 2 [4 Marks]