Heat Transfer Apparatus: Heating and Cooling

Some changes that occur when an object is heated are so slight that they cannot be seen. Rods and wires expand in diameter as well as in length when heated, and they return to their original size when cooled. The expansion frame is designed to “magnify” the effect. As a rod expands, the pointer is pushed up by a correspondingly larger amount. Two rods can be compared at a time. These may be of different materials (aluminum, copper, brass, glass).