Gay-Lussac law (volume–temperature)

Statement

V/T = const at constant pressure — the volume of a fixed amount of gas is proportional to its absolute temperature T (in kelvins).

Why is it true?

It's one "half" of the ideal-gas equation PV = nRT: holding P fixed gives V ∝ T. The other half — Boyle's law — states V ∝ 1/P at constant temperature.

Gay-Lussac's experiment showed all gases expand almost identically when heated — a feature that only appears when temperature is measured on an absolute (kelvin) scale, which this discovery itself pushed Lord Kelvin to propose.

Applications

Hot-air balloons and airships, Stirling engines, predicting gas volume in containers, explaining tire blowouts on hot days.

Topics that use this theorem

Related theorems

Step-by-step proofs