BAR AND GAUGE
- This apparatus is used for illustrating expansion by heating and contraction by cooling.
- It consists of a mild steel bar 110×10 mm (length), mounted on a rod with a wooden handle, overall length approx. 280mm; with a cast metal gauge.
- The gauge has a cut-out that allows for a sliding fit over the ends of the bar, at room temperature.
- Also the gauge has a hole (10mm bore) in one arm that allows the bar to pass endways, only when cold.
- However when the metal bar is heated, it does not fit into the gauge . When allowed to cool, the bar will fit into the gauge again.
- Thus, heating the bar and then comparing it to the gauge provides an excellent visual demonstration of thermal expansion.