Charles's law – constant-pressure gas experiment

PhysicsThermal Physics & GasesAges 17–18

A column of air is trapped in a narrow glass tube by a mercury pellet, and the tube stands in a beaker of water that is heated or cooled. The mercury pellet moves by itself so the gas pressure stays constant; students read the temperature and volume, fill in a data table and plot V against t. Extended, the straight line through the data points meets the temperature axis at about −273 °C (0 K), while V/T stays constant.