Passage III

Solids, liquids, and gases usually expand when heated. Three experiments were conducted by scientists to study the expansion of different substances.

Experiment 1

The apparatus shown in Diagram 1 was used to measure the linear expansion of wires of the same length made from different metals. In each trial, a wire was connected to a voltage source, run through a series of pulleys, then attached to a weight. The temperature of the wire was varied by changing the amount of voltage applied. The amount of expansion is directly proportional to the rotation of the final pulley. The results are shown in Figure 1.

Experiment 2

A sample of liquid was placed in a stoppered test tube fitted with a graduated capillary tube and the test tube was then placed in a temperature-controlled water bath (Diagram 2). The rise of the liquid in the capillary tube was then measured at different temperatures. The results for 3 liquids are shown in Figure 2.

Experiment 3

A 20 mL sample of a gas in a gas syringe at room temperature (20°C) was placed in a temperature-controlled water bath (Diagram 3). Changes in gas volume as the temperature increased were measured for 3 gases. The results are shown in Figure 3.