Charles's Law
An ideal gas law stating that gas volume is directly proportional to absolute thermodynamic temperature at constant pressure.
Governing formula
V1 / T1 = V2 / T2 (at constant P)
SI unit
m³/K
In depth
Heating gas increases average molecular speed; to maintain constant pressure against external atmosphere, the gas must expand into a larger volume.
Examples in the real world
A hot air balloon expanding as burner flames heat the air inside, lowering its density so it floats upward.