Charles's Law

Charles's law: at constant pressure, V/T = constant for an ideal gas (T in Kelvin).

Equivalently: V₁/T₁ = V₂/T₂ at constant P.

DIRECT proportionality between V and absolute T.

On V-T graph: straight line through origin.

Extrapolating V to zero gives T = 0 K = −273.15°C = ABSOLUTE ZERO.

Microscopically: higher T ⇒ faster molecules ⇒ more momentum transfer ⇒ gas expands at constant P.

Discovered by Jacques Charles (1787) and later refined by Joseph Gay-Lussac.

Special case of ideal gas law at constant P and n.