In a popular lecture demonstration, a sheet of paper is wrapped around a rod that is made from wood on one half and metal on the other half. If held over a flame, the paper on one half of the rod is burned while the paper on the other half is unaffected.
(a) Is the burned paper on the wooden half of the rod, or on the metal half of the rod?
(b) Choose the best explanation from among the following:
I. The metal will be hotter to the touch than the wood; therefore the metal side will be burnt.
II. The metal conducts heat better than the wood, and hence the paper on the metal half is unaffected.
III. The metal has the smaller specific heat; hence it heats up more and burns the paper on its half of the rod.