Physic f.4

metal is a very good heat conductor especially the aluminium,thus it can provide a even distribution of heat ,but why it needs to be sandwiched by two layers of stainless steel,it is because aluminium will form an oxide easily with the air ,it will affect the conductivity of heat ,but sandwished with a layer of stainless steel ,which is highly corrosion resistance ,and also a quite good heat conducor ,can prevent the aluminium to form oxide ,and thus maintain a good conductivity of heat.