Principle

Metal tubes are heated with steam. The linear expansion of three
different metals is determined with the aid of a rotating-shaft
pointer. From this the metals’ coefficient of linear expansion is
determined (Supplementary problem). The use of a rolling-shaft
pointer is advantageous because the resulting indication of
expansion is frictionless. The functional principle of a
rotating-shaft pointer can be easily demonstrated in a simple
experiment and studied by the students. The students should do this
before they calculate the change in length Δl in
"Evaluation".