Charles’s Law

Charles’s Law

Charles’s law states that when keeping the pressure constant, the volume of a gas varies directly with the temperature. Charles’s law equation can be represented as V α T.


V = Volume of the gas,

T = Temperature.

This law dictates the linear relationship that volume shares with temperature. The temperatures are conventionally measured in Kelvin, the SI unit of temperature.  At a given pressure, the volume of a given mass of a gas is proportional to its absolute temperature. This is known as Charles’s law.

From Kinetic theory of gases, if P is constant, V α v²rms.

As v²rms α T, we get V α T which is Charles’s law.

V/ T = Constant

V₁/ T₁ = V₂/ T₂

V/ T = m/ ρT = Constant (As Volume (V) = m/ ρ)

ρT = Constant

ρ₁T₁ = ρ₂T₂.

Thus, V – T graph is a straight line passing through origin (or) V/T versus V or T graph is a straight line parallel to V or T axis.

Charles’s Law