Phy Chapter 9 Expansion Heat Caltec S.3

15.1 Expansion and Contraction Expansion is the increase in size or an object when it gets hotter. While contraction is the decrease in size of an object when it becomes colder. (a) Expansion of solids All solids expand when heat is applied to them. However, they do so in varying amounts. Some solids expand very little while others expand greatly. Expansion in solids can be investigated by using the following experiments. The ball and ring. The bar and gauge Experiments to investigate the effect of heat on solids Experiment 15.1 Ball and ring experiment Apparatus/Requirements A ball and ring, source of heat Procedure Part I Pass the ball through the ring when cool as shown in figure 15.1 below. Figure 15.1 Observation: The ball passes through the ring easily. Part II Heat the ball on a Bunsen burner for some time. Try to pass it through the hole again. Observation: The ball does not pass through. Explanation: When the ball is heated, it expands i.e. the size becomes bigger. As such, it can not pass through the ring. Expedient 15.2 The bar and gauge experiment Apparatus/Requirements A bar and gauge, source of heat Procedure: Part I Pass one end of the bar through the hole on the gauge. Remove the bar and fix it in between the ends of the gauge as shown in figures 15.2 (a) and (b). Observation: The head of the bar passes through the hole and also fits in the gauge easily. Part II Heat the bar on a Bunsen burner flame for some time. Try to pass it through the hole and also try to fix it in the gauge. 0bservation: The head of the bar does not pass through the hole and does not fit in the gauge. Allow the bar and the ball …