The Boyle’s Law & Charles’ Law combined apparatus is the classic arrangement consisting of an open and a closed glass tube joined by a rubber hose and filled with mercury (not supplied). The system is mounted on a 1m high calibrated rail and the heights of the components are adjustable. The difference with this item is that the kit contains the extra components to convert the system from Boyle’s Law to Charles’ Law. This makes it more expensive than Boyle’s.
For Boyle’s Law: The volume inside the closed glass tube is measured on the scale and the pressure applied to the air is calculated from the difference in heights of the mercury surfaces in the tubes. At a constant temperature, the formula P x V = k (constant) is demonstrated and proven. For Charles’ Law, the gas is heated and the volume is kept constant by raising the pressure on the gas. The relationship between temperature, volume and pressure is discovered.